U.S. patent application number 17/406804 was filed with the patent office on 2022-03-24 for resource reservation for sidelink communications in shared radio frequency spectrum.
The applicant listed for this patent is QUALCOMM Incorporated. Invention is credited to Peter Gaal, Chih-Hao Liu, Tao Luo, Juan Montojo, Jing Sun, Yisheng Xue, Xiaoxia Zhang.
Application Number | 20220095117 17/406804 |
Document ID | / |
Family ID | |
Filed Date | 2022-03-24 |
United States Patent
Application |
20220095117 |
Kind Code |
A1 |
Liu; Chih-Hao ; et
al. |
March 24, 2022 |
RESOURCE RESERVATION FOR SIDELINK COMMUNICATIONS IN SHARED RADIO
FREQUENCY SPECTRUM
Abstract
Methods, systems, and devices for wireless communications are
described in which a first user equipment (UE) may transmit a first
communication to a second UE during a first channel occupancy time
(COT). The first UE may reserve resources of one or more subsequent
COTs for one or more repetitions of the first communication. The
reserved resources may be identified based at least in part on a
two stage resource reservation, in which reserved resources are
identified relative to a timing of the one or more subsequent COTs.
Such a UE may first determine a timing of a second COT and may then
determine a timing of the reserved resources based on the timing of
the second COT. The reserved resources may be identified based at
least in part on one or more offsets from a starting time of the
second COT.
Inventors: |
Liu; Chih-Hao; (San Diego,
CA) ; Xue; Yisheng; (San Diego, CA) ; Sun;
Jing; (San Diego, CA) ; Zhang; Xiaoxia; (San
Diego, CA) ; Luo; Tao; (San Diego, CA) ; Gaal;
Peter; (San Diego, CA) ; Montojo; Juan; (San
Diego, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
QUALCOMM Incorporated |
San Diego |
CA |
US |
|
|
Appl. No.: |
17/406804 |
Filed: |
August 19, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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63081769 |
Sep 22, 2020 |
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International
Class: |
H04W 16/14 20060101
H04W016/14; H04W 74/08 20060101 H04W074/08; H04W 72/04 20060101
H04W072/04 |
Claims
1. A method for wireless communication at a first user equipment
(UE), comprising: transmitting a first communication to at least a
second UE during a first channel occupancy time of the first UE for
sidelink communications in a shared radio frequency spectrum band;
reserving at least a first resource for a retransmission of the
first communication in a second channel occupancy time for sidelink
communications in the shared radio frequency spectrum band, wherein
the first resource is indicated relative to a start time of the
second channel occupancy time; determining, after the reserving,
the start time of the second channel occupancy time in the shared
radio frequency spectrum band; and retransmitting the first
communication to at least the second UE using the first resource,
wherein a timing for the first resource is based at least in part
on the determined start time of the second channel occupancy
time.
2. The method of claim 1, further comprising: transmitting, to one
or more other UEs, sidelink control information that indicates one
or more of the first channel occupancy time or the second channel
occupancy time.
3. The method of claim 2, wherein the transmitting the sidelink
control information comprises: transmitting, within the first
channel occupancy time, two or more instances of the sidelink
control information, wherein each instance of the sidelink control
information indicates the first channel occupancy time.
4. The method of claim 3, wherein each instance of the sidelink
control information indicates an offset between the instance of the
sidelink control information and a start of the first channel
occupancy time.
5. The method of claim 1, wherein the reserving the first resource
comprises: transmitting, to one or more other UEs, an indication of
a relative slot offset between the start time of the second channel
occupancy time and the first resource.
6. The method of claim 5, wherein the indication of the relative
slot offset between the start time of the second channel occupancy
time and the first resource is indicated in a sidelink control
information transmission.
7. The method of claim 1, wherein the determining the start time of
the second channel occupancy time comprises: determining that a
listen-before-talk procedure associated with the second channel
occupancy time has obtained the shared radio frequency spectrum
band for the sidelink communications; and determining the start
time of the second channel occupancy time based at least in part on
a completion time of the listen-before-talk procedure.
8. The method of claim 1, wherein the first resource expires based
at least in part on a predetermined window after the first
communication, and wherein the predetermined window corresponds to
a predetermined number of channel occupancy times after the first
communication, a predetermined time period after the first
communication, or any combinations thereof
9. The method of claim 1, further comprising: transmitting, during
the second channel occupancy time, an indication that the first
resource is used or unused for retransmission of the first
communication, wherein the indication is provided in sidelink
control information that is transmitted during the second channel
occupancy time.
10. The method of claim 9, wherein the sidelink control information
includes a bitmap that provides the indication, wherein each bit of
the bitmap corresponds to a reserved resource in the second channel
occupancy time.
11. The method of claim 1, wherein the second channel occupancy
time is obtained by a third UE for sidelink communications in the
shared radio frequency spectrum band, and wherein the method
further comprises: receiving, from the third UE, sidelink control
information that identifies the second channel occupancy time and a
shared channel occupancy time for the sidelink communications in
the shared radio frequency spectrum band.
12. The method of claim 11, wherein the timing of the first
resource is based at least in part on the sidelink control
information from the third UE, and wherein the first resource is
indicated by one or more of a slot offset to a channel occupancy
time that is obtained by a different UE, a slot offset to a
boundary of the second channel occupancy time that is obtained by
the third UE, or a slot offset from a start of the shared channel
occupancy time that is indicated by the third UE.
13. The method of claim 12, wherein the sidelink control
information from the third UE indicates a duration of the shared
channel occupancy time, and wherein the timing of the first
resource is determined based at least in part on the duration of
the shared channel occupancy time.
14. The method of claim 12, wherein a reservation of the first
resource expires based at least in part on a predetermined window
after the first communication, one or more shared channel occupancy
times subsequent to the first communication, or any combinations
thereof
15. The method of claim 1, further comprising: receiving, from a
third UE, sidelink control information that indicates a shared
channel occupancy time and a zone identification; and determining
whether the shared channel occupancy time is available as the
second channel occupancy time based at least in part on the zone
identification.
16. The method of claim 15, further comprising: determining that a
distance between the first UE and a location associated with the
zone identification is less than a threshold value, and wherein the
shared channel occupancy time is available as the second channel
occupancy time based at least in part on the distance being less
than the threshold value.
17. A method for wireless communication at a second user equipment
(UE), comprising: receiving, from a first UE, a first communication
during a first channel occupancy time for sidelink communications
in a shared radio frequency spectrum band; receiving, from the
first UE, an indication of at least a first reserved resource for a
retransmission of the first communication in a second channel
occupancy time for sidelink communications in the shared radio
frequency spectrum band, wherein the first reserved resource is
indicated relative to a start time of the second channel occupancy
time; determining, after the first channel occupancy time, the
start time of the second channel occupancy time in the shared radio
frequency spectrum band; and identifying a timing for the first
reserved resource based at least in part on the determined start
time of the second channel occupancy time.
18. The method of claim 17, further comprising: receiving, from the
first UE, sidelink control information that indicates one or more
of the first channel occupancy time, the second channel occupancy
time, the indication of the first reserved resource, or any
combinations thereof
19. The method of claim 18, wherein the first UE transmits two or
more instances of the sidelink control information, wherein each
instance of the sidelink control information indicates the first
channel occupancy time and an offset between the instance of the
sidelink control information and a start of a channel occupancy
time associated with the sidelink control information.
20. The method of claim 17, wherein the indication of at least the
first reserved resource includes a relative slot offset between the
start time of the second channel occupancy time and the first
reserved resource.
21. The method of claim 17, wherein the first reserved resource
expires based at least in part on a predetermined window after the
first communication, and wherein the predetermined window
corresponds to a predetermined number of channel occupancy times
after the first communication, a predetermined time period after
the first communication, or any combinations thereof.
22. The method of claim 17, further comprising: receiving, during
the second channel occupancy time, an indication that the first
reserved resource is used or unused for retransmission of the first
communication; and monitoring for the retransmission of the first
communication based on the indication that the first reserved
resource is used for the retransmission of the first
communication.
23. The method of claim 17, wherein the second channel occupancy
time is obtained by a third UE for sidelink communications in the
shared radio frequency spectrum band, and wherein the method
further comprises: receiving, from the third UE, sidelink control
information that identifies the second channel occupancy time and a
shared channel occupancy time for the sidelink communications in
the shared radio frequency spectrum band.
24. The method of claim 17, further comprising: receiving, from a
third UE, sidelink control information that indicates a shared
channel occupancy time and a zone identification; and determining
whether the shared channel occupancy time is available as the
second channel occupancy time based at least in part on the zone
identification.
25. An apparatus for wireless communication at a first user
equipment (UE), comprising: a processor, memory coupled with the
processor; and instructions stored in the memory and executable by
the processor to cause the apparatus to: transmit a first
communication to at least a second UE during a first channel
occupancy time of the first UE for sidelink communications in a
shared radio frequency spectrum band; reserve at least a first
resource for a retransmission of the first communication in a
second channel occupancy time for sidelink communications in the
shared radio frequency spectrum band, wherein the first resource is
indicated relative to a start time of the second channel occupancy
time; determine, after the reserving, the start time of the second
channel occupancy time in the shared radio frequency spectrum band;
and retransmit the first communication to at least the second UE
using the first resource, wherein a timing for the first resource
is based at least in part on the determined start time of the
second channel occupancy time.
26. The apparatus of claim 25, wherein the instructions are further
executable by the processor to cause the apparatus to: transmit, to
one or more other UEs, sidelink control information that indicates
one or more of the first channel occupancy time or the second
channel occupancy time.
27. The apparatus of claim 26, wherein the instructions are further
executable by the processor to cause the apparatus to: transmit,
within the first channel occupancy time, two or more instances of
the sidelink control information, wherein each instance of the
sidelink control information indicates the first channel occupancy
time.
28. An apparatus for wireless communication at a second user
equipment (UE), comprising: a processor, memory coupled with the
processor; and instructions stored in the memory and executable by
the processor to cause the apparatus to: receive, from a first UE,
a first communication during a first channel occupancy time for
sidelink communications in a shared radio frequency spectrum band;
receive, from the first UE, an indication of at least a first
reserved resource for a retransmission of the first communication
in a second channel occupancy time for sidelink communications in
the shared radio frequency spectrum band, wherein the first
reserved resource is indicated relative to a start time of the
second channel occupancy time; determine, after the first channel
occupancy time, the start time of the second channel occupancy time
in the shared radio frequency spectrum band; and identify a timing
for the first reserved resource based at least in part on the
determined start time of the second channel occupancy time.
29. The apparatus of claim 28, wherein the instructions are further
executable by the processor to cause the apparatus to: receive,
from the first UE, sidelink control information that indicates one
or more of the first channel occupancy time, the second channel
occupancy time, the indication of the first reserved resource, or
any combinations thereof
30. The apparatus of claim 29, wherein the first UE transmits two
or more instances of the sidelink control information, wherein each
instance of the sidelink control information indicates the first
channel occupancy time and an offset between the instance of the
sidelink control information and a start of a channel occupancy
time associated with the sidelink control information.
Description
CROSS REFERENCE
[0001] The present Application for Patent claims the benefit of
U.S. Provisional Patent Application No. 63/081,769 by LIU et al.,
entitled "RESOURCE RESERVATION FOR SIDELINK COMMUNICATIONS IN
SHARED RADIO FREQUENCY SPECTRUM," filed Sep. 22, 2020, assigned to
the assignee hereof, and expressly incorporated by reference
herein.
FIELD OF TECHNOLOGY
[0002] The following relates to wireless communications, including
resource reservation for sidelink communications in shared radio
frequency spectrum.
BACKGROUND
[0003] Wireless communications systems are widely deployed to
provide various types of communication content such as voice,
video, packet data, messaging, broadcast, and so on. These systems
may be capable of supporting communication with multiple users by
sharing the available system resources (e.g., time, frequency, and
power). Examples of such multiple-access systems include fourth
generation (4G) systems such as Long Term Evolution (LTE) systems,
LTE-Advanced (LTE-A) systems, or LTE-A Pro systems, and fifth
generation (5G) systems which may be referred to as New Radio (NR)
systems. These systems may employ technologies such as code
division multiple access (CDMA), time division multiple access
(TDMA), frequency division multiple access (FDMA), orthogonal
frequency division multiple access (OFDMA), or discrete Fourier
transform spread orthogonal frequency division multiplexing
(DFT-S-OFDM). A wireless multiple-access communications system may
include one or more base stations or one or more network access
nodes, each simultaneously supporting communication for multiple
communication devices, which may be otherwise known as user
equipment (UE).
[0004] In some deployments, UEs may communicate with one or more
base stations using an access link (e.g., via a Uu interface in a
4G or 5G system). Further, some UEs may communicate directly with
one or more other UEs using a sidelink (e.g., a PC5 interface),
such that the UEs communicate directly rather than through a base
station for some communications. In some cases, reliability of
communications between UEs may be enhanced through one or more
repetitions of a transmission, in which a transmitting UE may
transmit two or more instances of a communication. Efficient
identification and use of sidelink resources in such deployments
may help to enhance the efficiency, reliability, and latency of a
network, and thus may be desirable.
SUMMARY
[0005] The described techniques relate to improved methods,
systems, devices, and apparatuses that support resource reservation
for sidelink communications in shared radio frequency spectrum. In
accordance with various aspects of the present disclosure, a first
user equipment (UE) may transmit a first communication to a second
UE during a first channel occupancy time (COT), and may reserve
resources of one or more subsequent COTs for one or more
repetitions of the first communication. In some cases, the reserved
resources may be identified based at least in part on a two stage
resource reservation, in which reserved resources are identified
relative to a timing of the one or more subsequent COTs. Such a UE
may first determine a timing of a second COT and may then determine
a timing of the reserved resources based on the timing of the
second COT. In some cases, the reserved resources may be identified
based at least in part on one or more offsets from a starting time
of the second COT. The first UE may transmit one or more additional
instances of the first communication using the reserved
resources.
[0006] In some cases, an indication of the reserved resources may
be provided with sidelink control information (SCI) that is
transmitted by the first UE. In some cases, one or more of the COTs
may be shared COTs that are obtained by a different UE than the
first UE. In some cases, the first UE may use reserved resources in
a shared COT based on a location of the first UE and a location of
a third UE that obtained the shared COT. In such cases, the first
UE may identify one or more reserved resources in the shared COT
for the one or more retransmissions when the first UE is within a
predetermined distance of the third UE. In some cases, the location
of the first UE relative to the third UE may be based at least on
one or more of a zone identification of the third UE matching the
zone identification of the first UE, a global navigation satellite
system (GNSS) location indication, or any combinations thereof.
[0007] A method of wireless communication at a first UE is
described. The method may include transmitting a first
communication to at least a second UE during a first channel
occupancy time of the first UE for sidelink communications in a
shared radio frequency spectrum band, reserving at least a first
resource for a retransmission of the first communication in a
second channel occupancy time for sidelink communications in the
shared radio frequency spectrum band, where the first resource is
indicated relative to a start time of the second channel occupancy
time, determining, after the reserving, the start time of the
second channel occupancy time in the shared radio frequency
spectrum band, identifying a timing for the first resource based on
the determined start time of the second channel occupancy time, and
retransmitting the first communication to at least the second UE
using the first resource.
[0008] An apparatus for wireless communication at a first UE is
described. The apparatus may include a processor, memory coupled
with the processor, and instructions stored in the memory. The
instructions may be executable by the processor to cause the
apparatus to transmit a first communication to at least a second UE
during a first channel occupancy time of the first UE for sidelink
communications in a shared radio frequency spectrum band, reserve
at least a first resource for a retransmission of the first
communication in a second channel occupancy time for sidelink
communications in the shared radio frequency spectrum band, where
the first resource is indicated relative to a start time of the
second channel occupancy time, determine, after the reserving, the
start time of the second channel occupancy time in the shared radio
frequency spectrum band, identify a timing for the first resource
based on the determined start time of the second channel occupancy
time, and retransmit the first communication to at least the second
UE using the first resource.
[0009] Another apparatus for wireless communication at a first UE
is described. The apparatus may include means for transmitting a
first communication to at least a second UE during a first channel
occupancy time of the first UE for sidelink communications in a
shared radio frequency spectrum band, reserving at least a first
resource for a retransmission of the first communication in a
second channel occupancy time for sidelink communications in the
shared radio frequency spectrum band, where the first resource is
indicated relative to a start time of the second channel occupancy
time, determining, after the reserving, the start time of the
second channel occupancy time in the shared radio frequency
spectrum band, identifying a timing for the first resource based on
the determined start time of the second channel occupancy time, and
retransmitting the first communication to at least the second UE
using the first resource.
[0010] A non-transitory computer-readable medium storing code for
wireless communication at a first UE is described. The code may
include instructions executable by a processor to transmit a first
communication to at least a second UE during a first channel
occupancy time of the first UE for sidelink communications in a
shared radio frequency spectrum band, reserve at least a first
resource for a retransmission of the first communication in a
second channel occupancy time for sidelink communications in the
shared radio frequency spectrum band, where the first resource is
indicated relative to a start time of the second channel occupancy
time, determine, after the reserving, the start time of the second
channel occupancy time in the shared radio frequency spectrum band,
identify a timing for the first resource based on the determined
start time of the second channel occupancy time, and retransmit the
first communication to at least the second UE using the first
resource.
[0011] Some examples of the method, apparatuses, and non-transitory
computer-readable medium described herein may further include
operations, features, means, or instructions for transmitting, to
one or more other UEs, sidelink control information that indicates
one or more of the first channel occupancy time or the second
channel occupancy time. In some examples of the method,
apparatuses, and non-transitory computer-readable medium described
herein, the transmitting the sidelink control information may
include operations, features, means, or instructions for
transmitting, within the first channel occupancy time, two or more
instances of the sidelink control information, where each instance
of the sidelink control information indicates the first channel
occupancy time. In some examples of the method, apparatuses, and
non-transitory computer-readable medium described herein, each
instance of the sidelink control information indicates an offset
between the instance of the sidelink control information and a
start of the first channel occupancy time.
[0012] In some examples of the method, apparatuses, and
non-transitory computer-readable medium described herein, the
reserving the first resource may include operations, features,
means, or instructions for transmitting, to one or more other UEs,
an indication of a relative slot offset between the start time of
the second channel occupancy time and the first resource. In some
examples of the method, apparatuses, and non-transitory
computer-readable medium described herein, the indication of the
relative slot offset between the start time of the second channel
occupancy time and the first resource is indicated in a sidelink
control information transmission.
[0013] In some examples of the method, apparatuses, and
non-transitory computer-readable medium described herein, the
determining the start time of the second channel occupancy time may
include operations, features, means, or instructions for
determining that a listen-before-talk procedure associated with the
second channel occupancy time has obtained the shared radio
frequency spectrum band for the sidelink communications, and
determining the start time of the second channel occupancy time
based on a completion time of the listen-before-talk procedure. In
some examples of the method, apparatuses, and non-transitory
computer-readable medium described herein, the first resource
expires based on a predetermined window after the first
communication. In some examples of the method, apparatuses, and
non-transitory computer-readable medium described herein, the
predetermined window corresponds to a predetermined number of
channel occupancy times after the first communication, a
predetermined time period after the first communication, or any
combinations thereof. In some examples of the method, apparatuses,
and non-transitory computer-readable medium described herein, the
reserving of at least the first resource includes reserving
periodic resources and the predetermined window applies to each
period of the periodic resources.
[0014] Some examples of the method, apparatuses, and non-transitory
computer-readable medium described herein may further include
operations, features, means, or instructions for transmitting,
during the second channel occupancy time, an indication that the
first resource is used or unused for retransmission of the first
communication. In some examples of the method, apparatuses, and
non-transitory computer-readable medium described herein, the
indication may be provided in sidelink control information that is
transmitted during the second channel occupancy time. In some
examples of the method, apparatuses, and non-transitory
computer-readable medium described herein, the sidelink control
information includes a bitmap that provides the indication, where
each bit of the bitmap corresponds to a reserved resource in the
second channel occupancy time.
[0015] In some examples of the method, apparatuses, and
non-transitory computer-readable medium described herein, the
second channel occupancy time may be obtained by a third UE for
sidelink communications in the shared radio frequency spectrum
band. Some examples of the method, apparatuses, and non-transitory
computer-readable medium described herein may further include
operations, features, means, or instructions for receiving, from
the third UE, sidelink control information that identifies the
second channel occupancy time and a shared channel occupancy time
for the sidelink communications in the shared radio frequency
spectrum band. In some examples of the method, apparatuses, and
non-transitory computer-readable medium described herein, the
timing of the first resource is based on the sidelink control
information from the third UE.
[0016] In some examples of the method, apparatuses, and
non-transitory computer-readable medium described herein, the first
resource is indicated by a slot offset to a channel occupancy time
that is obtained by a different UE. In some examples of the method,
apparatuses, and non-transitory computer-readable medium described
herein, the first resource is indicated by a slot offset to a
boundary of the second channel occupancy time that is obtained by
the third UE. In some examples of the method, apparatuses, and
non-transitory computer-readable medium described herein, the first
resource is indicated by a slot offset from a start of the shared
channel occupancy time that is indicated by the third UE. In some
examples of the method, apparatuses, and non-transitory
computer-readable medium described herein, the sidelink control
information from the third UE indicates a duration of the shared
channel occupancy time, and where the timing of the first resource
is determined based on the duration of the shared channel occupancy
time. In some examples of the method, apparatuses, and
non-transitory computer-readable medium described herein, a
reservation of the first resource expires based on a predetermined
window after the first communication, one or more shared channel
occupancy times subsequent to the first communication, or any
combinations thereof
[0017] Some examples of the method, apparatuses, and non-transitory
computer-readable medium described herein may further include
operations, features, means, or instructions for receiving, from a
third UE, sidelink control information that indicates a shared
channel occupancy time and a zone identification, and determining
whether the shared channel occupancy time is available as the
second channel occupancy time based on the zone identification.
Some examples of the method, apparatuses, and non-transitory
computer-readable medium described herein may further include
operations, features, means, or instructions for determining that a
distance between the first UE and a location associated with the
zone identification is less than a threshold value, and where the
shared channel occupancy time is available as the second channel
occupancy time based on the distance being less than the threshold
value. In some examples of the method, apparatuses, and
non-transitory computer-readable medium described herein, the
location associated with the zone identification is a location of
the third UE. Some examples of the method, apparatuses, and
non-transitory computer-readable medium described herein may
further include operations, features, means, or instructions for
determining, based on a global navigation satellite system, a first
location of the first UE, and where the determining that the
distance is less than the threshold value is based on the first
location and the location associated with the zone identification.
In some examples of the method, apparatuses, and non-transitory
computer-readable medium described herein, the zone identification
corresponds to a group identification provided by a network node,
and where the shared channel occupancy time is available as the
second channel occupancy time when the group identification of the
first UE is the same as the group identification of the third
UE.
[0018] In some examples of the method, apparatuses, and
non-transitory computer-readable medium described herein, the
sidelink control information from the third UE is forwarded by one
or more other UEs. In some examples of the method, apparatuses, and
non-transitory computer-readable medium described herein, the one
or more other UEs act as relay nodes for the sidelink control
information and include a UE identification of the third UE that
obtained the second channel occupancy time.
[0019] A method of wireless communication at a second UE is
described. The method may include receiving, from a first UE, a
first communication during a first channel occupancy time for
sidelink communications in a shared radio frequency spectrum band,
receiving, from the first UE, an indication of at least a first
reserved resource for a retransmission of the first communication
in a second channel occupancy time for sidelink communications in
the shared radio frequency spectrum band, where the first reserved
resource is indicated relative to a start time of the second
channel occupancy time, determining, after the first channel
occupancy time, the start time of the second channel occupancy time
in the shared radio frequency spectrum band, and identifying a
timing for the first reserved resource based on the determined
start time of the second channel occupancy time.
[0020] An apparatus for wireless communication at a second UE is
described. The apparatus may include a processor, memory coupled
with the processor, and instructions stored in the memory. The
instructions may be executable by the processor to cause the
apparatus to receive, from a first UE, a first communication during
a first channel occupancy time for sidelink communications in a
shared radio frequency spectrum band, receive, from the first UE,
an indication of at least a first reserved resource for a
retransmission of the first communication in a second channel
occupancy time for sidelink communications in the shared radio
frequency spectrum band, where the first reserved resource is
indicated relative to a start time of the second channel occupancy
time, determine, after the first channel occupancy time, the start
time of the second channel occupancy time in the shared radio
frequency spectrum band, and identify a timing for the first
reserved resource based on the determined start time of the second
channel occupancy time.
[0021] Another apparatus for wireless communication at a second UE
is described. The apparatus may include means for receiving, from a
first UE, a first communication during a first channel occupancy
time for sidelink communications in a shared radio frequency
spectrum band, receiving, from the first UE, an indication of at
least a first reserved resource for a retransmission of the first
communication in a second channel occupancy time for sidelink
communications in the shared radio frequency spectrum band, where
the first reserved resource is indicated relative to a start time
of the second channel occupancy time, determining, after the first
channel occupancy time, the start time of the second channel
occupancy time in the shared radio frequency spectrum band, and
identifying a timing for the first reserved resource based on the
determined start time of the second channel occupancy time.
[0022] A non-transitory computer-readable medium storing code for
wireless communication at a second UE is described. The code may
include instructions executable by a processor to receive, from a
first UE, a first communication during a first channel occupancy
time for sidelink communications in a shared radio frequency
spectrum band, receive, from the first UE, an indication of at
least a first reserved resource for a retransmission of the first
communication in a second channel occupancy time for sidelink
communications in the shared radio frequency spectrum band, where
the first reserved resource is indicated relative to a start time
of the second channel occupancy time, determine, after the first
channel occupancy time, the start time of the second channel
occupancy time in the shared radio frequency spectrum band, and
identify a timing for the first reserved resource based on the
determined start time of the second channel occupancy time.
[0023] Some examples of the method, apparatuses, and non-transitory
computer-readable medium described herein may further include
operations, features, means, or instructions for receiving, from
the first UE, sidelink control information that indicates one or
more of the first channel occupancy time, the second channel
occupancy time, the indication of the first reserved resource, or
any combinations thereof. In some examples of the method,
apparatuses, and non-transitory computer-readable medium described
herein, the first UE transmits two or more instances of the
sidelink control information, where each instance of the sidelink
control information indicates the first channel occupancy time and
an offset between the instance of the sidelink control information
and a start of a channel occupancy time associated with the
sidelink control information. In some examples of the method,
apparatuses, and non-transitory computer-readable medium described
herein, the indication of at least the first reserved resource
includes a relative slot offset between the start time of the
second channel occupancy time and the first reserved resource. In
some examples of the method, apparatuses, and non-transitory
computer-readable medium described herein, the first resource
expires based on a predetermined window after the first
communication, and where the predetermined window corresponds to a
predetermined number of channel occupancy times after the first
communication, a predetermined time period after the first
communication, or any combinations thereof. Some examples of the
method, apparatuses, and non-transitory computer-readable medium
described herein may further include operations, features, means,
or instructions for receiving, during the second channel occupancy
time, an indication that the first resource is used or unused for
retransmission of the first communication, and monitoring for the
retransmission of the first communication based on the indication
that the first resource is used for the retransmission of the first
communication.
[0024] In some examples of the method, apparatuses, and
non-transitory computer-readable medium described herein, the
second channel occupancy time is obtained by a third UE for
sidelink communications in the shared radio frequency spectrum
band. Some examples of the method, apparatuses, and non-transitory
computer-readable medium described herein may further include
operations, features, means, or instructions for receiving, from
the third UE, sidelink control information that identifies the
second channel occupancy time and a shared channel occupancy time
for the sidelink communications in the shared radio frequency
spectrum band. In some examples of the method, apparatuses, and
non-transitory computer-readable medium described herein, the
timing of the first reserved resource is based on the sidelink
control information from the third UE. In some examples of the
method, apparatuses, and non-transitory computer-readable medium
described herein, the first reserved resource is indicated by a
slot offset to a boundary of the second channel occupancy time that
is obtained by the third UE. In some examples of the method,
apparatuses, and non-transitory computer-readable medium described
herein, the first resource is indicated by a slot offset from a
start of the shared channel occupancy time that is indicated by the
third UE.
[0025] Some examples of the method, apparatuses, and non-transitory
computer-readable medium described herein may further include
operations, features, means, or instructions for receiving, from a
third UE, sidelink control information that indicates a shared
channel occupancy time and a zone identification, and determining
whether the shared channel occupancy time is available as the
second channel occupancy time based on the zone identification. In
some examples of the method, apparatuses, and non-transitory
computer-readable medium described herein, the zone identification
corresponds to a group identification provided by a network node,
and where the shared channel occupancy time is available as the
second channel occupancy time when the group identification of the
first UE is the same as the group identification of the third UE.
In some examples of the method, apparatuses, and non-transitory
computer-readable medium described herein, the sidelink control
information from the third UE is forwarded by one or more other
UEs.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIG. 1 illustrates an example of a system for wireless
communications that supports resource reservation for sidelink
communications in shared radio frequency spectrum in accordance
with aspects of the present disclosure.
[0027] FIG. 2 illustrates an example of a portion of a wireless
communications system that supports resource reservation for
sidelink communications in shared radio frequency spectrum in
accordance with aspects of the present disclosure.
[0028] FIG. 3 illustrates an example of reserved resources in COTs
that support sidelink communications in shared radio frequency
spectrum in accordance with aspects of the present disclosure.
[0029] FIGS. 4 and 5 illustrate examples of shared COTs that
support resource reservation for sidelink communications in shared
radio frequency spectrum in accordance with aspects of the present
disclosure.
[0030] FIGS. 6 and 7 illustrate examples of portions of wireless
communications systems that support resource reservation for
sidelink communications in shared radio frequency spectrum in
accordance with aspects of the present disclosure.
[0031] FIGS. 8 and 9 illustrate examples of a process flows that
support resource reservation for sidelink communications in shared
radio frequency spectrum in accordance with aspects of the present
disclosure.
[0032] FIGS. 10 and 11 show block diagrams of devices that support
resource reservation for sidelink communications in shared radio
frequency spectrum in accordance with aspects of the present
disclosure.
[0033] FIG. 12 shows a block diagram of a communications manager
that supports resource reservation for sidelink communications in
shared radio frequency spectrum in accordance with aspects of the
present disclosure.
[0034] FIG. 13 shows a diagram of a system including a device that
supports resource reservation for sidelink communications in shared
radio frequency spectrum in accordance with aspects of the present
disclosure.
[0035] FIGS. 14 through 22 show flowcharts illustrating methods
that support resource reservation for sidelink communications in
shared radio frequency spectrum in accordance with aspects of the
present disclosure.
DETAILED DESCRIPTION
[0036] Some wireless communications systems may support both access
links and sidelinks. An access link is a communication link between
a user equipment (UE) and a base station. In some examples, an
access link may be referred to as a Uu interface. Specifically, the
Uu interface may refer to an over-the-air interface for downlink
transmissions, uplink transmissions, or both. A sidelink is a
communication link between similar devices and in some cases may be
referred to as a PC5 interface. For example, a sidelink may support
communications between multiple UEs (e.g., in a
vehicle-to-everything (V2X) system, a vehicle-to-vehicle (V2V)
system, a device-to-device (D2D) system, among other examples)
between multiple base stations (e.g., in an integrated access and
backhaul (IAB) deployment), or between other types of wireless
communications devices. It is noted that while various examples
provided herein are discussed for UE sidelink devices, techniques
discussed herein may be used for any type of wireless devices that
use shared radio frequency channels in which one or more instances
of a communication transmitted in a first channel occupancy time
(COT) may be retransmitted in one or more subsequent COTs based on
a resource reservation of the transmitting device. For example, a
sidelink may support one or more of D2D communications, V2X or V2V
communications, message relaying, discovery signaling, beacon
signaling, or other signals transmitted over-the-air from one
wireless device to one or more other similar wireless devices.
[0037] In some cases, a base station may configure a set of
resources for use in sidelink communications between UEs. For
example, the base station may configure frame and slot timing,
which may be used for UEs in sidelink communications. In some
cases, the configured resources for sidelink UEs may include shared
or unlicensed radio frequency spectrum in which devices that are to
access a channel perform a contention-based channel access
procedure that provides fair channel access to the unlicensed or
shared radio frequency spectrum. For example, a UE may perform a
listen before talk (LBT) procedure (e.g., a clear channel
assessment (CCA)) and determine whether signals from another device
are detected on a channel or sub-channel. In the event that other
signals are not detected that are indicative of another device
using the channel, the UE may determine that the channel is
available and transmit a reservation signal to indicate to other
UEs that the channel is reserved for a channel occupancy time
(COT).
[0038] As discussed herein, in some cases a UE may transmit one or
more repetitions of a communication in order to enhance the
likelihood of successful reception of the communication. Such
techniques may be used, for example, in cases where a communication
has a high priority, where the communication has a relatively low
latency target, where channel conditions are relatively
unfavorable, or any combinations thereof. In systems that use
licensed radio frequency spectrum, the availability of a channel to
transmit one or more of such repetitions may be known based on
scheduling of resources for UE communications. Thus, in such cases,
a UE may be identify a set of resources for a communication and one
or more sets of resources for repetitions of the communication. The
communication and associated resources may then be transmitted
using the identified resources. However, in cases where unlicensed
or shared radio frequency spectrum is used for such communications,
the availability of the channel may be dependent upon a
successfully completed contention-based channel access procedure
(e.g., a LBT or CCA procedure). Accordingly, resources for one or
more repetitions of a communication may not be known if the
repetitions are to occur in one or more subsequent COTs.
[0039] In accordance with various aspects described herein,
resource reservations for one or more repetitions of a
communication may be identified relative to a COT, and determined
based on a COT timing. In some cases, a first UE may transmit a
first communication to a second UE during a first COT, and may
reserve resources of one or more subsequent COTs for one or more
repetitions of the first communication. In some cases, the reserved
resources may be identified based at least in part on a two stage
resource reservation, in which reserved resources are identified
relative to a timing of the one or more subsequent COTs. Such a UE
may first determine a timing of a second COT and may then determine
a timing of the reserved resources based on the timing of the
second COT. In some cases, the reserved resources may be identified
based at least in part on one or more offsets from a starting time
of the second COT. The first UE may transmit one or more additional
instances of the first communication using the reserved
resources.
[0040] In some cases, an indication of the reserved resources may
be provided with sidelink control information (SCI) that is
transmitted by the first UE. In some cases, one or more of the COTs
may be shared COTs that are obtained by a different UE than the
first UE. In some cases, the first UE may use reserved resources in
a shared COT based on a location of the first UE and a location of
a third UE that obtained the shared COT. In such cases, the first
UE may identify one or more reserved resources in the shared COT
for the one or more retransmissions when the first UE is within a
predetermined distance of the third UE. In some cases, the location
of the first UE relative to the third UE may be based at least on
one or more of a zone identification of the third UE matching the
zone identification of the first UE, a global navigation satellite
system (GNSS) location indication, or any combinations thereof.
[0041] Various aspects of the subject matter described herein may
be implemented to realize one or more of the following potential
advantages. The techniques employed by the described base stations
and UEs may provide benefits and enhancements to the operation of a
wireless communications system. For example, operations performed
by the UEs may provide improvements to reliability and efficiency
in communications using shared radio frequency spectrum with
sidelink UEs and other devices that may contend for channel access
to the shared radio frequency spectrum. Such improvements may
enhance efficiency of wireless communications at a UE by allowing
for reliable transmission and retransmission of communications,
which may enhance the likelihood of successful receipt of the
communications at a receiving device. The described techniques may
thus include features for improvements to reliability in
communications, and enhanced communications efficiency for sidelink
UEs and other devices that use shared radio frequency spectrum
through reduced channel contention procedures associated with
retransmissions, among other benefits.
[0042] Aspects of the disclosure are initially described in the
context of wireless communications systems. Various examples of
resource reservations based on COT timing and UE location are then
discussed. Aspects of the disclosure are further illustrated by and
described with reference to apparatus diagrams, system diagrams,
and flowcharts that relate to resource reservation for sidelink
communications in shared radio frequency spectrum.
[0043] FIG. 1 illustrates an example of a wireless communications
system 100 that supports resource reservation for sidelink
communications in shared radio frequency spectrum in accordance
with aspects of the present disclosure. The wireless communications
system 100 may include one or more base stations 105, one or more
UEs 115, and a core network 130. In some examples, the wireless
communications system 100 may be a Long Term Evolution (LTE)
network, an LTE-Advanced (LTE-A) network, an LTE-A Pro network, or
a New Radio (NR) network. In some examples, the wireless
communications system 100 may support enhanced broadband
communications, ultra-reliable (e.g., mission critical)
communications, low latency communications, communications with
low-cost and low-complexity devices, or any combination
thereof.
[0044] The base stations 105 may be dispersed throughout a
geographic area to form the wireless communications system 100 and
may be devices in different forms or having different capabilities.
The base stations 105 and the UEs 115 may wirelessly communicate
via one or more communication links 125. Each base station 105 may
provide a coverage area 110 over which the UEs 115 and the base
station 105 may establish one or more communication links 125. The
coverage area 110 may be an example of a geographic area over which
a base station 105 and a UE 115 may support the communication of
signals according to one or more radio access technologies.
[0045] The UEs 115 may be dispersed throughout a coverage area 110
of the wireless communications system 100, and each UE 115 may be
stationary, or mobile, or both at different times. The UEs 115 may
be devices in different forms or having different capabilities.
Some example UEs 115 are illustrated in FIG. 1. The UEs 115
described herein may be able to communicate with various types of
devices, such as other UEs 115, the base stations 105, or network
equipment (e.g., core network nodes, relay devices, integrated
access and backhaul (IAB) nodes, or other network equipment), as
shown in FIG. 1.
[0046] The base stations 105 may communicate with the core network
130, or with one another, or both. For example, the base stations
105 may interface with the core network 130 through one or more
backhaul links 120 (e.g., via an S1, N2, N3, or other interface).
The base stations 105 may communicate with one another over the
backhaul links 120 (e.g., via an X2, Xn, or other interface) either
directly (e.g., directly between base stations 105), or indirectly
(e.g., via core network 130), or both. In some examples, the
backhaul links 120 may be or include one or more wireless
links.
[0047] One or more of the base stations 105 described herein may
include or may be referred to by a person having ordinary skill in
the art as a base transceiver station, a radio base station, an
access point, a radio transceiver, a NodeB, an eNodeB (eNB), a
next-generation NodeB or a giga-NodeB (either of which may be
referred to as a gNB), a Home NodeB, a Home eNodeB, or other
suitable terminology.
[0048] A UE 115 may include or may be referred to as a mobile
device, a wireless device, a remote device, a handheld device, or a
subscriber device, or some other suitable terminology, where the
"device" may also be referred to as a unit, a station, a terminal,
or a client, among other examples. A UE 115 may also include or may
be referred to as a personal electronic device such as a cellular
phone, a personal digital assistant (PDA), a tablet computer, a
laptop computer, or a personal computer. In some examples, a UE 115
may include or be referred to as a wireless local loop (WLL)
station, an Internet of Things (IoT) device, an Internet of
Everything (IoE) device, or a machine type communications (MTC)
device, among other examples, which may be implemented in various
objects such as appliances, or vehicles, meters, among other
examples.
[0049] The UEs 115 described herein may be able to communicate with
various types of devices, such as other UEs 115 that may sometimes
act as relays as well as the base stations 105 and the network
equipment including macro eNBs or gNBs, small cell eNBs or gNBs, or
relay base stations, among other examples, as shown in FIG. 1.
[0050] The UEs 115 and the base stations 105 may wirelessly
communicate with one another via one or more communication links
125 over one or more carriers. The term "carrier" may refer to a
set of radio frequency spectrum resources having a defined physical
layer structure for supporting the communication links 125. For
example, a carrier used for a communication link 125 may include a
portion of a radio frequency spectrum band (e.g., a bandwidth part
(BWP)) that is operated according to one or more physical layer
channels for a given radio access technology (e.g., LTE, LTE-A,
LTE-A Pro, NR). Each physical layer channel may carry acquisition
signaling (e.g., synchronization signals, system information),
control signaling that coordinates operation for the carrier, user
data, or other signaling. The wireless communications system 100
may support communication with a UE 115 using carrier aggregation
or multi-carrier operation. A UE 115 may be configured with
multiple downlink component carriers and one or more uplink
component carriers according to a carrier aggregation
configuration. Carrier aggregation may be used with both frequency
division duplexing (FDD) and time division duplexing (TDD)
component carriers.
[0051] In some examples (e.g., in a carrier aggregation
configuration), a carrier may also have acquisition signaling or
control signaling that coordinates operations for other carriers. A
carrier may be associated with a frequency channel (e.g., an
evolved universal mobile telecommunication system terrestrial radio
access (E-UTRA) absolute radio frequency channel number (EARFCN))
and may be positioned according to a channel raster for discovery
by the UEs 115. A carrier may be operated in a standalone mode
where initial acquisition and connection may be conducted by the
UEs 115 via the carrier, or the carrier may be operated in a
non-standalone mode where a connection is anchored using a
different carrier (e.g., of the same or a different radio access
technology).
[0052] The communication links 125 shown in the wireless
communications system 100 may include uplink transmissions from a
UE 115 to a base station 105, or downlink transmissions from a base
station 105 to a UE 115. Carriers may carry downlink or uplink
communications (e.g., in an FDD mode) or may be configured to carry
downlink and uplink communications (e.g., in a TDD mode).
[0053] A carrier may be associated with a particular bandwidth of
the radio frequency spectrum, and in some examples the carrier
bandwidth may be referred to as a "system bandwidth" of the carrier
or the wireless communications system 100. For example, the carrier
bandwidth may be one of a number of determined bandwidths for
carriers of a particular radio access technology (e.g., 1.4, 3, 5,
10, 15, 20, 40, or 80 megahertz (MHz)). Devices of the wireless
communications system 100 (e.g., the base stations 105, the UEs
115, or both) may have hardware configurations that support
communications over a particular carrier bandwidth or may be
configurable to support communications over one of a set of carrier
bandwidths. In some examples, the wireless communications system
100 may include base stations 105 or UEs 115 that support
simultaneous communications via carriers associated with multiple
carrier bandwidths. In some examples, each served UE 115 may be
configured for operating over portions (e.g., a sub-band, a BWP) or
all of a carrier bandwidth.
[0054] Signal waveforms transmitted over a carrier may be made up
of multiple subcarriers (e.g., using multi-carrier modulation (MCM)
techniques such as orthogonal frequency division multiplexing
(OFDM) or discrete Fourier transform spread OFDM (DFT-S-OFDM)). In
a system employing MCM techniques, a resource element may consist
of one symbol period (e.g., a duration of one modulation symbol)
and one subcarrier, where the symbol period and subcarrier spacing
are inversely related. The number of bits carried by each resource
element may depend on the modulation scheme (e.g., the order of the
modulation scheme, the coding rate of the modulation scheme, or
both). Thus, the more resource elements that a UE 115 receives and
the higher the order of the modulation scheme, the higher the data
rate may be for the UE 115. A wireless communications resource may
refer to a combination of a radio frequency spectrum resource, a
time resource, and a spatial resource (e.g., spatial layers or
beams), and the use of multiple spatial layers may further increase
the data rate or data integrity for communications with a UE
115.
[0055] One or more numerologies for a carrier may be supported,
where a numerology may include a subcarrier spacing (.DELTA.f) and
a cyclic prefix. A carrier may be divided into one or more BWPs
having the same or different numerologies. In some examples, a UE
115 may be configured with multiple BWPs. In some examples, a
single BWP for a carrier may be active at a given time and
communications for the UE 115 may be restricted to one or more
active BWPs.
[0056] The time intervals for the base stations 105 or the UEs 115
may be expressed in multiples of a basic time unit which may, for
example, refer to a sampling period of
T.sub.s=1/(.DELTA.f.sub.maxN.sub.f) seconds, where .DELTA.f.sub.max
may represent the maximum supported subcarrier spacing, and N.sub.f
may represent the maximum supported discrete Fourier transform
(DFT) size. Time intervals of a communications resource may be
organized according to radio frames each having a specified
duration (e.g., 10 milliseconds (ms)). Each radio frame may be
identified by a system frame number (SFN) (e.g., ranging from 0 to
1023).
[0057] Each frame may include multiple consecutively numbered
subframes or slots, and each subframe or slot may have the same
duration. In some examples, a frame may be divided (e.g., in the
time domain) into subframes, and each subframe may be further
divided into a number of slots. Alternatively, each frame may
include a variable number of slots, and the number of slots may
depend on subcarrier spacing. Each slot may include a number of
symbol periods (e.g., depending on the length of the cyclic prefix
prepended to each symbol period). In some wireless communications
systems 100, a slot may further be divided into multiple mini-slots
containing one or more symbols. Excluding the cyclic prefix, each
symbol period may contain one or more (e.g., N.sub.f) sampling
periods. The duration of a symbol period may depend on the
subcarrier spacing or frequency band of operation.
[0058] A subframe, a slot, a mini-slot, or a symbol may be the
smallest scheduling unit (e.g., in the time domain) of the wireless
communications system 100 and may be referred to as a transmission
time interval (TTI). In some examples, the TTI duration (e.g., the
number of symbol periods in a TTI) may be variable. Additionally or
alternatively, the smallest scheduling unit of the wireless
communications system 100 may be dynamically selected (e.g., in
bursts of shortened TTIs (sTTIs)).
[0059] Physical channels may be multiplexed on a carrier according
to various techniques. A physical control channel and a physical
data channel may be multiplexed on a downlink carrier, for example,
using one or more of time division multiplexing (TDM) techniques,
frequency division multiplexing (FDM) techniques, or hybrid TDM-FDM
techniques. A control region (e.g., a control resource set
(CORESET)) for a physical control channel may be defined by a
number of symbol periods and may extend across the system bandwidth
or a subset of the system bandwidth of the carrier. One or more
control regions (e.g., CORESETs) may be configured for a set of the
UEs 115. For example, one or more of the UEs 115 may monitor or
search control regions for control information according to one or
more search space sets, and each search space set may include one
or multiple control channel candidates in one or more aggregation
levels arranged in a cascaded manner. An aggregation level for a
control channel candidate may refer to a number of control channel
resources (e.g., control channel elements (CCEs)) associated with
encoded information for a control information format having a given
payload size. Search space sets may include common search space
sets configured for sending control information to multiple UEs 115
and UE-specific search space sets for sending control information
to a specific UE 115.
[0060] Each base station 105 may provide communication coverage via
one or more cells, for example a macro cell, a small cell, a hot
spot, or other types of cells, or any combination thereof. The term
"cell" may refer to a logical communication entity used for
communication with a base station 105 (e.g., over a carrier) and
may be associated with an identifier for distinguishing neighboring
cells (e.g., a physical cell identifier (PCID), a virtual cell
identifier (VCID), or others). In some examples, a cell may also
refer to a geographic coverage area 110 or a portion of a
geographic coverage area 110 (e.g., a sector) over which the
logical communication entity operates. Such cells may range from
smaller areas (e.g., a structure, a subset of structure) to larger
areas depending on various factors such as the capabilities of the
base station 105. For example, a cell may be or include a building,
a subset of a building, or exterior spaces between or overlapping
with geographic coverage areas 110, among other examples.
[0061] A macro cell generally covers a relatively large geographic
area (e.g., several kilometers in radius) and may allow
unrestricted access by the UEs 115 with service subscriptions with
the network provider supporting the macro cell. A small cell may be
associated with a lower-powered base station 105, as compared with
a macro cell, and a small cell may operate in the same or different
(e.g., licensed, unlicensed) frequency bands as macro cells. Small
cells may provide unrestricted access to the UEs 115 with service
subscriptions with the network provider or may provide restricted
access to the UEs 115 having an association with the small cell
(e.g., the UEs 115 in a closed subscriber group (CSG), the UEs 115
associated with users in a home or office). A base station 105 may
support one or multiple cells and may also support communications
over the one or more cells using one or multiple component
carriers.
[0062] In some examples, a carrier may support multiple cells, and
different cells may be configured according to different protocol
types (e.g., MTC, narrowband IoT (NB-IoT), enhanced mobile
broadband (eMBB)) that may provide access for different types of
devices.
[0063] In some examples, a base station 105 may be movable and
therefore provide communication coverage for a moving geographic
coverage area 110. In some examples, different geographic coverage
areas 110 associated with different technologies may overlap, but
the different geographic coverage areas 110 may be supported by the
same base station 105. In other examples, the overlapping
geographic coverage areas 110 associated with different
technologies may be supported by different base stations 105. The
wireless communications system 100 may include, for example, a
heterogeneous network in which different types of the base stations
105 provide coverage for various geographic coverage areas 110
using the same or different radio access technologies.
[0064] The wireless communications system 100 may support
synchronous or asynchronous operation. For synchronous operation,
the base stations 105 may have similar frame timings, and
transmissions from different base stations 105 may be approximately
aligned in time. For asynchronous operation, the base stations 105
may have different frame timings, and transmissions from different
base stations 105 may, in some examples, not be aligned in time.
The techniques described herein may be used for either synchronous
or asynchronous operations.
[0065] Some UEs 115, such as MTC or IoT devices, may be low cost or
low complexity devices and may provide for automated communication
between machines (e.g., via Machine-to-Machine (M2M)
communication). M2M communication or MTC may refer to data
communication technologies that allow devices to communicate with
one another or a base station 105 without human intervention. In
some examples, M2M communication or MTC may include communications
from devices that integrate sensors or meters to measure or capture
information and relay such information to a central server or
application program that makes use of the information or presents
the information to humans interacting with the application program.
Some UEs 115 may be designed to collect information or enable
automated behavior of machines or other devices. Examples of
applications for MTC devices include smart metering, inventory
monitoring, water level monitoring, equipment monitoring,
healthcare monitoring, wildlife monitoring, weather and geological
event monitoring, fleet management and tracking, remote security
sensing, physical access control, and transaction-based business
charging.
[0066] Some UEs 115 may be configured to employ operating modes
that reduce power consumption, such as half-duplex communications
(e.g., a mode that supports one-way communication via transmission
or reception, but not transmission and reception simultaneously).
In some examples, half-duplex communications may be performed at a
reduced peak rate. Other power conservation techniques for the UEs
115 include entering a power saving deep sleep mode when not
engaging in active communications, operating over a limited
bandwidth (e.g., according to narrowband communications), or a
combination of these techniques. For example, some UEs 115 may be
configured for operation using a narrowband protocol type that is
associated with a defined portion or range (e.g., set of
subcarriers or resource blocks (RBs)) within a carrier, within a
guard-band of a carrier, or outside of a carrier.
[0067] The wireless communications system 100 may be configured to
support ultra-reliable communications or low-latency
communications, or various combinations thereof. For example, the
wireless communications system 100 may be configured to support
ultra-reliable low-latency communications (URLLC) or mission
critical communications. The UEs 115 may be designed to support
ultra-reliable, low-latency, or critical functions (e.g., mission
critical functions). Ultra-reliable communications may include
private communication or group communication and may be supported
by one or more mission critical services such as mission critical
push-to-talk (MCPTT), mission critical video (MCVideo), or mission
critical data (MCData). Support for mission critical functions may
include prioritization of services, and mission critical services
may be used for public safety or general commercial applications.
The terms ultra-reliable, low-latency, mission critical, and
ultra-reliable low-latency may be used interchangeably herein.
[0068] In some examples, a UE 115 may also be able to communicate
directly with other UEs 115 over a device-to-device (D2D)
communication link 135 (e.g., using a peer-to-peer (P2P) or D2D
protocol). One or more UEs 115 utilizing D2D communications may be
within the geographic coverage area 110 of a base station 105.
Other UEs 115 in such a group may be outside the geographic
coverage area 110 of a base station 105 or be otherwise unable to
receive transmissions from a base station 105. In some examples,
groups of the UEs 115 communicating via D2D communications may
utilize a one-to-many (1:M) system in which each UE 115 transmits
to every other UE 115 in the group. In some examples, a base
station 105 facilitates the scheduling of resources for D2D
communications. In other cases, D2D communications are carried out
between the UEs 115 without the involvement of a base station
105.
[0069] In some systems, the D2D communication link 135 may be an
example of a communication channel, such as a sidelink
communication channel, between vehicles (e.g., UEs 115). In some
examples, vehicles may communicate using vehicle-to-everything
(V2X) communications, vehicle-to-vehicle (V2V) communications, or
some combination of these. A vehicle may signal information related
to traffic conditions, signal scheduling, weather, safety,
emergencies, or any other information relevant to a V2X system. In
some examples, vehicles in a V2X system may communicate with
roadside infrastructure, such as roadside units, or with the
network via one or more network nodes (e.g., base stations 105)
using vehicle-to-network (V2N) communications, or with both.
[0070] The core network 130 may provide user authentication, access
authorization, tracking, Internet Protocol (IP) connectivity, and
other access, routing, or mobility functions. The core network 130
may be an evolved packet core (EPC) or 5G core (5GC), which may
include at least one control plane entity that manages access and
mobility (e.g., a mobility management entity (MME), an access and
mobility management function (AMF)) and at least one user plane
entity that routes packets or interconnects to external networks
(e.g., a serving gateway (S-GW), a Packet Data Network (PDN)
gateway (P-GW), or a user plane function (UPF)). The control plane
entity may manage non-access stratum (NAS) functions such as
mobility, authentication, and bearer management for the UEs 115
served by the base stations 105 associated with the core network
130. User IP packets may be transferred through the user plane
entity, which may provide IP address allocation as well as other
functions. The user plane entity may be connected to the network
operators IP services 150. The network operators IP services 150
may include access to the Internet, Intranet(s), an IP Multimedia
Subsystem (IMS), or a Packet-Switched Streaming Service.
[0071] Some of the network devices, such as a base station 105, may
include subcomponents such as an access network entity 140, which
may be an example of an access node controller (ANC). Each access
network entity 140 may communicate with the UEs 115 through one or
more other access network transmission entities 145, which may be
referred to as radio heads, smart radio heads, or
transmission/reception points (TRPs). Each access network
transmission entity 145 may include one or more antenna panels. In
some configurations, various functions of each access network
entity 140 or base station 105 may be distributed across various
network devices (e.g., radio heads and ANCs) or consolidated into a
single network device (e.g., a base station 105).
[0072] The wireless communications system 100 may operate using one
or more frequency bands, typically in the range of 300 megahertz
(MHz) to 300 gigahertz (GHz). Generally, the region from 300 MHz to
3 GHz is known as the ultra-high frequency (UHF) region or
decimeter band because the wavelengths range from approximately one
decimeter to one meter in length. The UHF waves may be blocked or
redirected by buildings and environmental features, but the waves
may penetrate structures sufficiently for a macro cell to provide
service to the UEs 115 located indoors. The transmission of UHF
waves may be associated with smaller antennas and shorter ranges
(e.g., less than 100 kilometers) compared to transmission using the
smaller frequencies and longer waves of the high frequency (HF) or
very high frequency (VHF) portion of the spectrum below 300
MHz.
[0073] The wireless communications system 100 may also operate in a
super high frequency (SHF) region using frequency bands from 3 GHz
to 30 GHz, also known as the centimeter band, or in an extremely
high frequency (EHF) region of the spectrum (e.g., from 30 GHz to
300 GHz), also known as the millimeter band. In some examples, the
wireless communications system 100 may support millimeter wave
(mmW) communications between the UEs 115 and the base stations 105,
and EHF antennas of the respective devices may be smaller and more
closely spaced than UHF antennas. In some examples, this may
facilitate use of antenna arrays within a device. The propagation
of EHF transmissions, however, may be subject to even greater
atmospheric attenuation and shorter range than SHF or UHF
transmissions. The techniques disclosed herein may be employed
across transmissions that use one or more different frequency
regions, and designated use of bands across these frequency regions
may differ by country or regulating body.
[0074] The wireless communications system 100 may utilize both
licensed and unlicensed radio frequency spectrum bands. For
example, the wireless communications system 100 may employ License
Assisted Access (LAA), LTE-Unlicensed (LTE-U) radio access
technology, or NR technology in an unlicensed band such as the 5
GHz industrial, scientific, and medical (ISM) band. When operating
in unlicensed radio frequency spectrum bands, devices such as the
base stations 105 and the UEs 115 may employ carrier sensing for
collision detection and avoidance. In some examples, operations in
unlicensed bands may be based on a carrier aggregation
configuration in conjunction with component carriers operating in a
licensed band (e.g., LAA). Operations in unlicensed spectrum may
include downlink transmissions, uplink transmissions, P2P
transmissions, or D2D transmissions, among other examples.
[0075] A base station 105 or a UE 115 may be equipped with multiple
antennas, which may be used to employ techniques such as transmit
diversity, receive diversity, multiple-input multiple-output (MIMO)
communications, or beamforming. The antennas of a base station 105
or a UE 115 may be located within one or more antenna arrays or
antenna panels, which may support MIMO operations or transmit or
receive beamforming. For example, one or more base station antennas
or antenna arrays may be co-located at an antenna assembly, such as
an antenna tower. In some examples, antennas or antenna arrays
associated with a base station 105 may be located in diverse
geographic locations. A base station 105 may have an antenna array
with a number of rows and columns of antenna ports that the base
station 105 may use to support beamforming of communications with a
UE 115. Likewise, a UE 115 may have one or more antenna arrays that
may support various MIMO or beamforming operations. Additionally or
alternatively, an antenna panel may support radio frequency
beamforming for a signal transmitted via an antenna port.
[0076] Beamforming, which may also be referred to as spatial
filtering, directional transmission, or directional reception, is a
signal processing technique that may be used at a transmitting
device or a receiving device (e.g., a base station 105, a UE 115)
to shape or steer an antenna beam (e.g., a transmit beam, a receive
beam) along a spatial path between the transmitting device and the
receiving device. Beamforming may be achieved by combining the
signals communicated via antenna elements of an antenna array such
that some signals propagating at particular orientations with
respect to an antenna array experience constructive interference
while others experience destructive interference. The adjustment of
signals communicated via the antenna elements may include a
transmitting device or a receiving device applying amplitude
offsets, phase offsets, or both to signals carried via the antenna
elements associated with the device. The adjustments associated
with each of the antenna elements may be defined by a beamforming
weight set associated with a particular orientation (e.g., with
respect to the antenna array of the transmitting device or
receiving device, or with respect to some other orientation).
[0077] The wireless communications system 100 may be a packet-based
network that operates according to a layered protocol stack. In the
user plane, communications at the bearer or Packet Data Convergence
Protocol (PDCP) layer may be IP-based. A Radio Link Control (RLC)
layer may perform packet segmentation and reassembly to communicate
over logical channels. A Medium Access Control (MAC) layer may
perform priority handling and multiplexing of logical channels into
transport channels. The MAC layer may also use error detection
techniques, error correction techniques, or both to support
retransmissions at the MAC layer to improve link efficiency. In the
control plane, the Radio Resource Control (RRC) protocol layer may
provide establishment, configuration, and maintenance of an RRC
connection between a UE 115 and a base station 105 or a core
network 130 supporting radio bearers for user plane data. At the
physical layer, transport channels may be mapped to physical
channels.
[0078] The UEs 115 and the base stations 105 may support
retransmissions of data to increase the likelihood that data is
received successfully. Hybrid automatic repeat request (HARQ)
feedback is one technique for increasing the likelihood that data
is received correctly over a communication link 125. HARQ may
include a combination of error detection (e.g., using a cyclic
redundancy check (CRC)), forward error correction (FEC), and
retransmission (e.g., automatic repeat request (ARQ)). HARQ may
improve throughput at the MAC layer in poor radio conditions (e.g.,
low signal-to-noise conditions). In some examples, a device may
support same-slot HARQ feedback, where the device may provide HARQ
feedback in a specific slot for data received in a previous symbol
in the slot. In other cases, the device may provide HARQ feedback
in a subsequent slot, or according to some other time interval.
[0079] In some cases, UEs 115 may use sidelink communications on
shared radio frequency spectrum, and identify retransmission
resources in accordance with various techniques as discussed
herein. In some cases, a UE 115 may transmit a first communication
during a first COT, and may reserve resources of one or more
subsequent COTs for one or more repetitions of the first
communication. The UE 115 may first determine a timing of a second
COT and may then determine a timing of the reserved resources based
on the timing of the second COT. In some cases, the reserved
resources may be identified based at least in part on one or more
offsets from a starting time of the second COT, and one or more
additional instances of the first communication may be transmitted
using the reserved resources.
[0080] FIG. 2 illustrates an example of a wireless communications
system 200 that supports resource reservation for sidelink
communications in shared radio frequency spectrum in accordance
with aspects of the present disclosure. In some examples, wireless
communications system 200 may implement aspects of wireless
communications system 100. Wireless communications system 200 may
include a base station 105-a, a first UE 115-a, and a second UE
115-b which may be examples of a base station 105 and UEs 115,
respectively, described with reference to FIG. 1. In some cases,
the first UE 115-a and the second UE 115-b may communicate with
each other (e.g., within a V2X system, a D2D system, and the like)
via sidelink communications.
[0081] In this example, each of the UEs 115 may be in a coverage
area 210 (e.g., a coverage area with reference to FIG. 1) of the
base station 105. In other examples, one or more UEs 115 may be
outside of the coverage area 210. The first UE 115-a, the second UE
115-b, or both, may communicate with the base station 105-a via a
respective access link (e.g., Uu links that may be used to provide
downlink and uplink communications via the Uu interface). Further,
UEs 115 may establish a sidelink (e.g., a PC5 link) that may be
used for direct communications between the first UE 115-a and the
second UE 115-b. It is noted that the example of FIG. 2 is provided
for purposes of discussion and illustration only, and numerous
other deployments are possible, such as cases where communications
between the base station 105-a and one or more UEs 115 are relayed
through another UE 115 (e.g., relayed using sidelink communications
215 when a UE 115 is outside of coverage area 110-a), cases where
additional UEs 115 are present, cases where other types of UEs 115
or relays are present (e.g., roadside units in a V2X system), cases
where UEs 115 are deployed in a factory automation or other
industrial setting, or any combinations thereof, to name but a few
examples. Techniques as discussed herein may be used in any such
deployments.
[0082] In accordance with techniques discussed herein, the base
station 105-a may provide configuration information to the first UE
115-a and the second UE 115-b related to sidelink communications.
Such configuration information may include, for example, an
indication of wireless resources that are allocated for sidelink
communications 215 between the first UE 115-a and the second UE
115-b, which may include resources that use unlicensed or shared
radio frequency spectrum. In the example of FIG. 2, the first UE
115-a may transmit a first communication 220 to the second UE 115-b
(and optionally one or more other UEs). For example, the first UE
115-a may perform a contention-based channel access procedure and
obtain a channel for a duration of a first COT that may be used to
transmit the first communication 220. In some cases, the sidelink
communications configuration may provide that the first UE 115-a
may reserve resources for one or more retransmissions of the first
communication 220 (e.g., the first UE 115-a may reserve resources
for up to 3 repetitions of a transmission in a periodic pattern in
which the period can be indicated in sidelink control information
(SCI) by a value of a number of slots between retransmissions).
[0083] In some cases, resources for one or more retransmissions may
be outside of the first COT that is used to transmit the first
communication 220. In such cases, one or more repetitions may be
transmitted in a subsequent COT, using resources that are
identified based on a two stage resource reservation. In some
cases, the first UE 115-a may perform a contention-based channel
access procedure (e.g., a category 4 LBT) and obtain the channel
for a second COT, and transmit a COT indication 225. The second COT
may include retransmission resources 230 for the one or more
repetitions of the first communication 220. In other cases, a
different UE 115 may obtain the COT that may be used for
retransmissions, and the first UE 115-a may use shared COT
resources to determine the retransmission resources 230. Thus,
different sidelink nodes may be a helper of other nodes by sharing
portions of a secured COT with other nodes. For the retransmissions
in a COT or a shared COT, the first UE 115-a may perform a shorter
contention-based channel access procedure (e.g., a category 1 or 2
LBT) and then transmit the one or more retransmissions.
[0084] In some cases, the first UE 115-a may determine a location
of retransmission resources based on a timing of a second COT. In
such cases, the first UE 115-a may identify the reserved resources
based at least in part on one or more offsets from a starting time
of the second COT, and the one or more additional repetitions of
the first communication may be transmitted using the reserved
resources. Such techniques may allow for retransmissions using
resources that are determined contingent on the first UE 115-a
having channel access, which may enhance the reliability of
sidelink communication relative to cases where reserved resources
are located at a fixed time relative to resources of the first
communication 220. Such techniques may also allow for reserved
resources to be located in different COTs, which can reduce a
density of reserved resources relative to cases where reserved
resources are located within a same COT as an initial transmission,
and also provide scheduling flexibility to schedule an initial
transmission relatively late in a COT and thereby enhance system
efficiency and reliability.
[0085] FIG. 3 illustrates an example of reserved resources in COTs
300 that supports resource reservation for sidelink communications
in shared radio frequency spectrum in accordance with aspects of
the present disclosure. In some examples, reserved resources in
COTs 300 may implement aspects of wireless communications system
100 or 200. In this example, a first UE (e.g., a UE 115 of FIG. 1
or 2) may identify a first COT 305 that is available for sidelink
communications with one or more other UEs, which includes a number
of slots 310. The first COT 305, and one or more subsequent COTs,
may be obtained directly by the first UE based on a LBT procedure
(e.g., a category 4 LBT). In other cases, a different UE may obtain
one or more COTs, as will be discussed in more detail with
reference to FIGS. 4 through 7.
[0086] In the example of FIG. 3, a LBT complete indication 315-a
may be provided for the first COT 305, which may be provided in a
COT indication 320, which may signal to other UEs that the first
COT 305 has been obtained and may indicate a duration of the COT.
The first COT 305 may include sidelink control resources 325 and
sidelink data resources 335, in accordance with a sidelink
configuration that is provided by a serving base station (e.g., a
base station of FIG. 1 or 2). The first UE may transmit SCI 330
that indicates that a first communication 340 is transmitted in the
sidelink data resources 335, and may also indicate reserved
resources 355 for one or more retransmissions of the first
communication 340. In some cases, the reserved resources 355 may be
located in a subsequent second COT 345 that is obtained based on a
subsequent LBT procedure of the first UE. In some cases, the SCI
330 indicates the reserved resources 355 relative to a timing of
the second COT 345, such as by indicating a first offset xo and a
second offset yo from a start of a COT indication 320 in the second
COT 345, from a start of a first slot 350-a of the second COT 345,
or from an end of a last slot 350-c of the second COT 345. In the
example of FIG. 3, offsets may be indicated relative to the COT
indication 320 and the first offset xo may indicate a first
instance of reserved resource 355-a in a second slot 350-b of the
second COT 345, and the second offset yo may indicate a second
instance of reserved resource 355-b in the last slot 350-c of the
second COT 345. Such offset indications to identify the reserved
resources 355 may reduce uncertainty associated with a location of
reserved resources 355 that may result in delays in scheduling due
to LBT procedures. Thus, the first UE may reserve resources inside
or outside of the current COT used for an initial instance of a
communication, depending on the timeline and COT duration.
[0087] In some cases, the reserved resources 355 may be indicated
in SCI 330, which may indicate the one or more offset values
relative to a start or end of a COT, and duration for the UE COT.
In some cases, COT parameters may be carried in SCIs in multiple
slots within the COT for COT detection robustness, and a receiving
UE may not be in a receive mode in a first slot 350-a of the second
COT 345. Thus, in some cases the indication of the reserved
resources 355 in the second COT 345 may be provided relative to an
end of the second COT 345. In other cases, the indication of the
reserved resources may be provided relative to the start of the
second COT 345, and the SCI 330 in later slots of a COT may
indicate the start of the associated COT (e.g., a number of symbols
since the start of the COT).
[0088] In some cases, reserved resources 355 may be valid for a
predetermined time window following the first communication 340.
For example, reserved resources 355 may be valid for a number of
upcoming COTs or a preset time window starting from the first
communication 340 or the first SCI 330 that indicates the reserved
resources 355. In some cases, the time window may be configured in
a sidelink configuration (e.g., provided by a serving base station
via RRC signaling), provided in a MAC-CE, provided in the SCI 330,
or any combinations thereof. In some cases, the reserved resources
355 may be periodic resources, and may be valid for a number of
COTs or a preset time window starting from the first reserved
resource SCI 330 in the beginning of each period. In some cases, a
UE may provide an explicit trigger for reserved resources 355 in an
upcoming COT that is obtained by the UE. For example, the UE may
provide an explicit reserved resource trigger in SCI 330 (e.g.,
SCI-1 or SCI-2) that carries COT information for one or multiple
reserved resources 355. In some cases, the reserved resource
trigger may be a bitmap for each individual reserved resource 355
within a COT.
[0089] FIG. 4 illustrates an example of a reserved resources in
shared COTs 400 that supports resource reservation for sidelink
communications in shared radio frequency spectrum in accordance
with aspects of the present disclosure. In some examples, reserved
resources in shared COTs 400 may implement aspects of wireless
communications system 100 or 200. In this example, multiple UEs may
share all or a portion of a COT with one or more other UEs, and
reserved resources for repetitions of communications may be
identified in shared COT resources.
[0090] For example, a first UE (e.g., a UE 115 of FIG. 1 or 2) may
perform a LBT to obtain a shared channel and provide a first UE COT
405 for communications of the first UE and a first shared COT 410
that may be used by other UEs. The first UE may provide an LBT
complete indication 415-a and a COT indication 440 that identifies
the first UE COT 405 and the first shared COT 410. Similarly, a
second UE may perform a LBT to obtain the shared channel and
provide a second UE COT 420 and a second shared COT 425, and a
third UE may perform a LBT to obtain the shared channel and provide
a third UE COT 430 and a third shared COT 435. Thus, each of the
UEs may provide some shared COT resources 455. In this example, the
first UE may transmit a first communication 460 in first UE COT
405, and may indicate a timing for one or more reserved resources
465 (e.g., in SCI 450 transmitted in sidelink control resources
445).
[0091] In some cases, the reserved resources 465 may be determined
based on a offset value xi relative to a start of a shared COT 425
or 435. In some cases, a UE that obtains a channel may signal
shared COT related parameters in SCI 450 to other UEs (e.g., in
groupcast SCI-2 or SCI-1). In some cases, the shared COT
information may be combined with SI-COT and may be signaled in any
slot before the shared COT start time (e.g., the shared COT
information may indicate an offset and duration of the shared COT).
By providing an indication of the reserved resources 456 relative
to a shared COT start time, the first UE may be able to reduce LBT
delay for retransmissions, as other UEs may act as helpers for
securing a COT and the first UE may then transmit on reserved
resources 465 using only a category 1 or 2 LBT (as opposed to a
category 4 LBT) in the shared COT. In some cases, the reserved
resources 465 may be indicated by the first UE in SCI 450 that
indicates the relative slot offset in the shared COT of a different
UE when the reserved resources 465 are outside of the first UE COT
405.
[0092] In some cases, the reserved resources 465 may be indicated
based on a relative slot offset with respect to the beginning or
the end of the COT of the different UE. In such cases, in the
non-shared COT region or the other UE, the LBT may be blocked by
the COT of the UE that obtained the channel, and the first UE may
use the shared COT region of the different UE using a category 1 or
2 LBT. In some cases, the reserved resources 465 may be indicated
based on a relative slot offset (e.g., x.sub.1) with respect to the
beginning of the indicated shared COT region, in which cases the
LBT is not blocked by the COT of the other UE. In some cases, a UE
may control whether to a COT is shared with other UEs, such as
discussed with reference to the example of FIG. 5.
[0093] FIG. 5 illustrates an example of a reserved resources in
shared COTs 500 that supports resource reservation for sidelink
communications in shared radio frequency spectrum in accordance
with aspects of the present disclosure. In some examples, reserved
resources in shared COTs 500 may implement aspects of wireless
communications system 100 or 200. In this example, multiple UEs may
share all or a portion of a COT with one or more other UEs, and
reserved resources for repetitions of communications may be
identified in shared COT resources 555.
[0094] For example, a first UE (e.g., a UE 115 of FIG. 1 or 2) may
perform a LBT to obtain a shared channel and provide a first UE COT
505 for communications of the first UE and a first shared COT 510
that may be used by other UEs. In this example a second UE may
transmit a second UE communication 570 in the first shared COT 510,
and the first UE may transmit a first UE communication 560 in the
first UE COT 505. The first UE may provide an LBT complete
indication 515 and a COT indication 540 that identifies the first
UE COT 505 and the first shared COT 510. In this example, the
second UE may perform a LBT to obtain the shared channel and
provide a second UE COT 520 that is unshared with other UEs. A
third UE may perform a LBT to obtain the shared channel and provide
a third UE COT 530 and a second shared COT 535. In this example,
the first UE may transmit the first UE communication 560 in first
UE COT 505, and may indicate a timing for one or more first UE
reserved resources 565 (e.g., in SCI 550 transmitted in sidelink
control resources 545).
[0095] In this example, the second UE may transmit a second UE
communication 570 in the first shared COT 510, and may indicate a
timing for associated second UE reserved resources 575. In some
cases, a UE may control whether to allow reserved resources from
other UEs by allowing COT sharing or not based on an indicated COT
sharing duration (e.g., that is indicated in SCI 550). If the
shared COT duration is zero, then other UEs have no reserved
resources in the current COT and will wait for next COT, and
reserved resources of the UE initiating the COT may be valid. In
the example of FIG. 5, the second UE reserved resources 575 are
valid in the second UE COT 520, but the first UE reserved resources
are not valid in the second UE COT 520, and thus the first UE waits
for a subsequent COT for retransmissions of the first UE
communication 560, either in its own COT or a shared COT of a
different UE. In this example, a third UE may provide second shared
COT 535, and the first UE reserved resources 565 may be identified
in the second shared COT 535 based on offset xi. Thus, in this
example, the third UE acts as a helper for other UE by clearing the
LBT and assigning the whole COT (except for the COT indication slot
at the beginning of COT) to all other UEs as a shared COT. In some
cases, a time window may be associated with reserved resources
following an initial communication by a UE, and reserved resources
associated with a transmission may expire based on an expiration of
the time window, similarly as discussed with reference to FIG. 3.
In some cases, when using a shared COT for a communication, a
hidden node may generate interference with a UE that is using a
shared COT of a different UE, such as in cases where the hidden
node is far enough away from the different UE that the COT
indication is not received but close enough to cause interference
with a UE that uses the shared COT. Examples of such hidden nodes
and techniques associated with same are discussed with reference to
FIGS. 6 and 7.
[0096] FIG. 6 illustrates an example of a portion of a wireless
communications system 600 that supports resource reservation for
sidelink communications in shared radio frequency spectrum in
accordance with aspects of the present disclosure. In some
examples, portion of a wireless communications system 600 may
implement aspects of wireless communications system 100 or 200. In
this example, a first UE 115-c may transmit a first UE
communication 605 to a second UE 115-d. In some cases, the first UE
115-c may use a portion of a shared COT that is obtained by a third
UE 115-e for a retransmission based on a resource reservation that
may be received by devices within a first UE resource reservation
SCI area 615.
[0097] In some cases, the third UE 115-e may have an associated
SI-COT area 610 in which devices within this area reliably receive
a COT indication from the third UE 115-e and refrain from
transmissions during the COT unless using a shared portion of the
COT in accordance with COT sharing techniques. However, a fourth UE
115-f may be outside of the SI-COT area 610 of the third UE 115-e.
Thus, the fourth UE 115-f may initiate a transmission during the
COT of the third UE 115-e, which may result in an interfering
transmission 620 that interferes with the first UE 115-c
communication 605. In some cases, the first UE 115-c may use the
shared COT of the third UE 115-e in cases where the first UE 115-c
and the third UE 115-e are relatively close to each other, and thus
the likelihood of a different UE (e.g., fourth UE 115-f)
transmitting using reserved resources of the first UE 115-c is
reduced. FIG. 7 illustrates an example of such proximity-based
determination of whether to use a shared COT.
[0098] FIG. 7 illustrates an example of a portion of a wireless
communications system 700 that supports resource reservation for
sidelink communications in shared radio frequency spectrum in
accordance with aspects of the present disclosure. In some
examples, portion of a wireless communications system 700 may
implement aspects of wireless communications system 100, 200, or
600. In this example, a first UE 115-g may transmit a first UE
communication 705 to a second UE 115-h. In some cases, the first UE
115-g may use a portion of a shared COT that is obtained by a third
UE 115-i for a retransmission based on a resource reservation that
may be received by devices within a first UE resource reservation
SCI area 715. In this example, the first UE 115-g may use the
shared COT of the third UE 115-i if the first UE 115-g is within a
maximum resource reservation area for COT sharing 720.
[0099] Similarly as in the example of FIG. 6, the third UE 115-i
may have an associated SI-COT area 710 in which devices within this
area reliably receive a COT indication from the third UE 115-i and
refrain from transmissions during the COT unless using a shared
portion of the COT in accordance with COT sharing techniques. In
this example, to prevent potential interference from the fourth UE
115-j, the first UE 115-g may use the shared COT if the first UE
115-g is within the maximum resource reservation area for COT
sharing 720 of the third UE 115-i. Such techniques may protect the
second UE 115-h from interference from the fourth UE 115-j, which
may be within the first UE resource reservation SCI area 715 but
not within the resource reservation area for COT sharing 720. In
some cases, the first UE 115-g may determine whether it is within a
predetermined distance of the third UE 115-i, and use the shared
COT based on the determination.
[0100] In some cases, the first UE 115-g may use the shared COT if
a zone identification of the third UE 115-i matches a zone
identification of the first UE 115-g, which may indicate that both
UEs are in a same sidelink cluster and relatively close in
proximity. In some cases, a zone identification may be included
with a COT sharing parameter transmitted by the third UE 115-i in
SCI, and other nodes use the shared COT only if they have the same
zone identification. In other cases, the first UE 115-g may
estimate a proximity to the third UE 115-i, and may use the shared
COT if the distance to the COT sharing UE is below a threshold
value. In such cases, each node may calculate the relative distance
based on the zone identification signaled in SI-COT and its
location. In other cases, proximity may be determined based on a
global navigation satellite system (GNSS) location (e.g., a global
positioning system (GPS) location provided by a GPS module), and
the first UE 115-g may use the shared COT only if a distance
between the UEs is below the threshold value. In other cases, a
serving base station may provide a network supervised sidelink
cluster, and the base station may group UEs that can share COTs.
For example, the base station may receive higher layer reporting
indicating SI-COTs that can be heard by different UEs, and may
group UEs based on which UEs are in proximity to each other. In
some cases, the base station may assign UEs a group ID for resource
reservation in COT sharing, and UEs with a same group ID may use
COT sharing for reserved resources.
[0101] In other cases, one or more other UEs may detect the third
UE 115-i COT sharing information and may forward and broadcast COT
sharing parameters to other nodes with layer 1 or layer 2
signaling. In such cases, the fourth UE 115-j may receive the
forwarded COT sharing information and avoid transmitting in the
reserved resource of the first UE 115-g that are within the shared
COT. For example, for layer 1 signaling, a COT detecting receiving
node can soft relay the COT sharing information to other nodes in
SCI, and provide a transcoded SI-COT bearing SCI that includes the
identification of the UE that is sharing its COT. In such cases,
the COT sharing region may be offset relative to the slot where the
soft relayed SCI is transmitted (e.g., the second UE 115-h may
forward the third UE 115-i COT sharing information to the fourth UE
115-j if it has a chance to communicate with the fourth UE 115-j
before or during the third UE 115-i COT sharing region).
[0102] FIG. 8 illustrates an example of a process flow 800 that
supports resource reservation for sidelink communications in shared
radio frequency spectrum in accordance with aspects of the present
disclosure. In some examples, process flow 800 may implement
aspects of wireless communications system 100, 200, 600, or 700.
Process flow 800 may be implemented by a first UE 115-k and a
second UE 115-l, which may be examples of UEs 115 as described
herein. Alternative examples of the following may be implemented,
where some steps are performed in a different order than described
or are not performed at all. In some cases, steps may include
additional features not mentioned below, or further steps may be
added.
[0103] At 805, the first UE 115-k may gain access to a shared
channel bandwidth for a first COT. In some cases, the first UE
115-k may perform a LBT procedure (e.g., a category 4 LBT) and gain
channel access for the first COT. At 810, the first UE 115-k may
transmit a first COT indicator to the second UE 115-1, and any
other UEs that are within a SCI area of the first UE 115-k. In some
cases, the first COT indicator may provide an indication of the
identity of the first UE 115-k, may provide an indication of a
duration of the first COT, may indicate one or more transmissions
and associated reserved resources for retransmissions, or any
combinations thereof
[0104] At 815, the first UE 115-k may determine a first
communication resources for a first communication to the second UE
115-l using the shared channel, and reserved resources for one or
more repetitions of the first communication. In some cases, the
reserved resources may be determined based on a configuration for
repetitions of communications (e.g., a number of slots between
repetitions, a number of repetitions, one or more offsets relative
to a COT timing, or any combinations thereof). At 820, the first UE
115-k may transmit the first communication to the second UE 115-1
using the identified resources in the first COT.
[0105] At 825, the first UE 115-k may gain access to the shared
channel bandwidth for a second COT. In some cases, the first UE
115-k may again perform a LBT procedure (e.g., a category 4 LBT)
and gain channel access for the second COT. At 830, the first UE
115-k may transmit a second COT indicator to the second UE 115-1,
and any other UEs that are within a SCI area of the first UE
115-k.
[0106] At 835, the first UE 115-k may identify reserved resources
within the second COT that are to be used for the one or more
retransmissions of the first communication. In some cases, the
reserved resources may be identified based on an offset relative to
a timing of the second COT, as discussed herein. At 840, the second
UE 115-l may also identify the reserved resources within the second
COT and monitor the identified resources for the one or more
retransmissions of the first communication. At 845, the first UE
115-k may transmit the one or more retransmissions of the first
communication.
[0107] FIG. 9 illustrates an example of a process flow 900 that
supports resource reservation for sidelink communications in shared
radio frequency spectrum in accordance with aspects of the present
disclosure. In some examples, process flow 900 may implement
aspects of wireless communications system 100, 200, 600, or 700.
Process flow 900 may be implemented by a first UE 115-m, a second
UE 115-n, and a third UE 115-o, which may be examples of UEs 115 as
described herein. Alternative examples of the following may be
implemented, where some steps are performed in a different order
than described or are not performed at all. In some cases, steps
may include additional features not mentioned below, or further
steps may be added.
[0108] At 905, the first UE 115-m may gain access to a shared
channel bandwidth for a first COT. In some cases, the first UE
115-m may perform a LBT procedure (e.g., a category 4 LBT) and gain
channel access for the first COT. At 910, the first UE 115-m may
transmit a first COT indicator to the second UE 115-n (which may
also be received at the third UE 115-o and one or more other UEs
that are within a SCI area of the first UE 115-m). In some cases,
the first COT indicator may provide an indication of the identity
of the first UE 115-m, may provide an indication of a duration of
the first COT, may indicate one or more transmissions and
associated reserved resources for retransmissions, or any
combinations thereof
[0109] At 915, the first UE 115-m may determine a first
communication resources for a first communication to the second UE
115-n using the shared channel, and reserved resources for one or
more repetitions of the first communication. In some cases, the
reserved resources may be determined based on a configuration for
repetitions of communications (e.g., a number of slots between
repetitions, a number of repetitions, one or more offsets relative
to a COT timing, or any combinations thereof). At 920, the first UE
115-m may transmit the first communication to the second UE 115-n
using the identified resources in the first COT.
[0110] At 925, the third UE 115-o may gain access to the shared
channel bandwidth for a shared COT. In some cases, the third UE
115-o may perform a LBT procedure (e.g., a category 4 LBT) and gain
channel access for the shared COT. At 930, the third UE 115-o may
transmit a shared COT indicator to the first UE 115-m and the
second UE 115-n (and one or more other UEs that are within a SCI
area of the third UE 115-o). In some cases, the shared COT
indicator may provide an indication of the identity of the third UE
115-o, and may provide an indication of a duration of a shared
portion of the shared COT.
[0111] At 935, the first UE 115-m may determine if the shared COT
is available for reserved resources of the first UE 115-m for
retransmission of the first communication. In some cases, such a
determination may be made based on a proximity between the first UE
115-m and the third UE 115-o, various examples of which are
discussed herein. At 940, the second UE 115-n may also identify
reserved resources within the shared COT that are to be monitored
for retransmissions based on the UE locations. At 945, if it is
determined that the shared COT is available for retransmissions on
the reserved resources, the first UE 115-m may transmit a
retransmission of the first communication.
[0112] FIG. 10 shows a block diagram 1000 of a device 1005 that
supports resource reservation for sidelink communications in shared
radio frequency spectrum in accordance with aspects of the present
disclosure. The device 1005 may be an example of aspects of a UE
115 as described herein. The device 1005 may include a receiver
1010, a communications manager 1015, and a transmitter 1020. The
device 1005 may also include a processor. Each of these components
may be in communication with one another (e.g., via one or more
buses).
[0113] The receiver 1010 may receive information such as packets,
user data, or control information associated with various
information channels (e.g., control channels, data channels, and
information related to resource reservation for sidelink
communications in shared radio frequency spectrum, etc.).
Information may be passed on to other components of the device
1005. The receiver 1010 may be an example of aspects of the
transceiver 1320 described with reference to FIG. 13. The receiver
1010 may utilize a single antenna or a set of antennas.
[0114] The communications manager 1015 may transmit a first
communication to at least a second UE during a first COT of the
first UE for sidelink communications in a shared radio frequency
spectrum band, reserve at least a first resource for a
retransmission of the first communication in a second COT for
sidelink communications in the shared radio frequency spectrum
band, where the first resource is indicated relative to a start
time of the second COT, determine, after the reserving, the start
time of the second COT in the shared radio frequency spectrum band,
identify a timing for the first resource based on the determined
start time of the second COT, and retransmit the first
communication to at least the second UE using the first
resource.
[0115] The communications manager 1015 may also receive, from a
first UE, a first communication during a first COT for sidelink
communications in a shared radio frequency spectrum band, receive,
from the first UE, an indication of at least a first reserved
resource for a retransmission of the first communication in a
second COT for sidelink communications in the shared radio
frequency spectrum band, where the first reserved resource is
indicated relative to a start time of the second COT, determine,
after the first COT, the start time of the second COT in the shared
radio frequency spectrum band, and identify a timing for the first
reserved resource based on the determined start time of the second
COT. The communications manager 1015 may be an example of aspects
of the communications manager 1310 described herein.
[0116] The communications manager 1015 as described herein may be
implemented to realize one or more potential advantages. One
implementation may allow the device 1005 to reliably determine
reserved resources for one or more retransmissions for one or more
sidelink communications. Such operations may provide improvements
to reliability and efficiency in communications with sidelink UEs
and with other UEs that may transmit or receive high priority or
low latency communications using shared radio frequency spectrum or
that otherwise gain channel access through a contention-based
channel access procedure. Such improvements may enhance efficiency
of wireless communications at a UE by allowing for reliable
identification of reserved resources in the sidelink resources. As
such, supported techniques may include improved network and UE
operations and, in some examples, may promote network efficiencies,
reduce latency, and provide network scheduling flexibility, among
other benefits.
[0117] The communications manager 1015, or its sub-components, may
be implemented in hardware, code (e.g., software or firmware)
executed by a processor, or any combination thereof. If implemented
in code executed by a processor, the functions of the
communications manager 1015, or its sub-components may be executed
by a general-purpose processor, a DSP, an application-specific
integrated circuit (ASIC), a FPGA or other programmable logic
device, discrete gate or transistor logic, discrete hardware
components, or any combination thereof designed to perform the
functions described in the present disclosure.
[0118] The communications manager 1015, or its sub-components, may
be physically located at various positions, including being
distributed such that portions of functions are implemented at
different physical locations by one or more physical components. In
some examples, the communications manager 1015, or its
sub-components, may be a separate and distinct component in
accordance with various aspects of the present disclosure. In some
examples, the communications manager 1015, or its sub-components,
may be combined with one or more other hardware components,
including but not limited to an input/output (I/O) component, a
transceiver, a network server, another computing device, one or
more other components described in the present disclosure, or a
combination thereof in accordance with various aspects of the
present disclosure.
[0119] The transmitter 1020 may transmit signals generated by other
components of the device 1005. In some examples, the transmitter
1020 may be collocated with a receiver 1010 in a transceiver
module. For example, the transmitter 1020 may be an example of
aspects of the transceiver 1320 described with reference to FIG.
13. The transmitter 1020 may utilize a single antenna or a set of
antennas.
[0120] FIG. 11 shows a block diagram 1100 of a device 1105 that
supports resource reservation for sidelink communications in shared
radio frequency spectrum in accordance with aspects of the present
disclosure. The device 1105 may be an example of aspects of a
device 1005, or a UE 115 as described herein. The device 1105 may
include a receiver 1110, a communications manager 1115, and a
transmitter 1135. The device 1105 may also include a processor.
Each of these components may be in communication with one another
(e.g., via one or more buses).
[0121] The receiver 1110 may receive information such as packets,
user data, or control information associated with various
information channels (e.g., control channels, data channels, and
information related to resource reservation for sidelink
communications in shared radio frequency spectrum, etc.).
Information may be passed on to other components of the device
1105. The receiver 1110 may be an example of aspects of the
transceiver 1320 described with reference to FIG. 13. The receiver
1110 may utilize a single antenna or a set of antennas.
[0122] The communications manager 1115 may be an example of aspects
of the communications manager 1015 as described herein. The
communications manager 1115 may include a sidelink communications
manager 1120, a resource reservation manager 1125, and a COT
manager 1130. The communications manager 1115 may be an example of
aspects of the communications manager 1310 described herein.
[0123] In some cases, the sidelink communications manager 1120 may
transmit a first communication to at least a second UE during a
first COT of the first UE for sidelink communications in a shared
radio frequency spectrum band. The resource reservation manager
1125 may reserve at least a first resource for a retransmission of
the first communication in a second COT for sidelink communications
in the shared radio frequency spectrum band, where the first
resource is indicated relative to a start time of the second COT.
The COT manager 1130 may determine, after the reserving, the start
time of the second COT in the shared radio frequency spectrum band.
The resource reservation manager 1125 may identify a timing for the
first resource based on the determined start time of the second
COT. The sidelink communications manager 1120 may retransmit the
first communication to at least the second UE using the first
resource.
[0124] In some cases, the sidelink communications manager 1120 may
receive, from a first UE, a first communication during a first COT
for sidelink communications in a shared radio frequency spectrum
band. The resource reservation manager 1125 may receive, from the
first UE, an indication of at least a first reserved resource for a
retransmission of the first communication in a second COT for
sidelink communications in the shared radio frequency spectrum
band, where the first reserved resource is indicated relative to a
start time of the second COT. The COT manager 1130 may determine,
after the first COT, the start time of the second COT in the shared
radio frequency spectrum band. The resource reservation manager
1125 may identify a timing for the first reserved resource based on
the determined start time of the second COT.
[0125] The transmitter 1135 may transmit signals generated by other
components of the device 1105. In some examples, the transmitter
1135 may be collocated with a receiver 1110 in a transceiver
module. For example, the transmitter 1135 may be an example of
aspects of the transceiver 1320 described with reference to FIG.
13. The transmitter 1135 may utilize a single antenna or a set of
antennas.
[0126] FIG. 12 shows a block diagram 1200 of a communications
manager 1205 that supports resource reservation for sidelink
communications in shared radio frequency spectrum in accordance
with aspects of the present disclosure. The communications manager
1205 may be an example of aspects of a communications manager 1015,
a communications manager 1115, or a communications manager 1310
described herein. The communications manager 1205 may include a
sidelink communications manager 1210, a resource reservation
manager 1215, a COT manager 1220, a SCI manager 1225, a LBT manager
1230, a shared COT manager 1235, and a location manager 1240. Each
of these modules may communicate, directly or indirectly, with one
another (e.g., via one or more buses).
[0127] The sidelink communications manager 1210 of a first UE may
transmit a first communication to at least a second UE during a
first COT of the first UE for sidelink communications in a shared
radio frequency spectrum band. In some examples, the sidelink
communications manager 1210 may retransmit the first communication
to at least the second UE using the first resource that is a
reserved resource for retransmissions.
[0128] In some examples, the sidelink communications manager 1210
of a second UE may receive, from a first UE, a first communication
during a first COT for sidelink communications in a shared radio
frequency spectrum band. In some examples, the sidelink
communications manager 1210 may monitor for the retransmission of
the first communication based on the indication that the first
resource is used for the retransmission of the first
communication.
[0129] The resource reservation manager 1215 of the first UE may
reserve at least a first resource for a retransmission of the first
communication in a second COT for sidelink communications in the
shared radio frequency spectrum band, where the first resource is
indicated relative to a start time of the second COT. In some
examples, the resource reservation manager 1215 may identify a
timing for the first resource based on the determined start time of
the second COT.
[0130] In some examples, the resource reservation manager 1215 at
the second UE may receive, from the first UE, an indication of at
least a first reserved resource for a retransmission of the first
communication in a second COT for sidelink communications in the
shared radio frequency spectrum band, where the first reserved
resource is indicated relative to a start time of the second COT.
In some examples, the resource reservation manager 1215 may
identify a timing for the first reserved resource based on the
determined start time of the second COT.
[0131] In some examples, the resource reservation manager 1215 of
the first UE may transmit, to one or more other UEs, an indication
of a relative slot offset between the start time of the second COT
and the first resource. In some cases, the indication of the
relative slot offset between the start time of the second COT and
the first resource is indicated in a SCI transmission.
[0132] In some cases, the first resource expires based on a
predetermined window after the first communication. In some cases,
the predetermined window corresponds to a predetermined number of
COTs after the first communication, a predetermined time period
after the first communication, or any combinations thereof. In some
cases, the reserving of at least the first resource includes
reserving periodic resources and the predetermined window applies
to each period of the periodic resources. In some cases, the
indication of at least the first reserved resource includes a
relative slot offset between the start time of the second COT and
the first reserved resource.
[0133] The COT manager 1220 may determine, after the reserving, the
start time of the second COT in the shared radio frequency spectrum
band.
[0134] The SCI manager 1225 may transmit, to one or more other UEs,
SCI that indicates one or more of the first COT or the second COT.
In some examples, the SCI manager 1225 may transmit, within the
first COT, two or more instances of the SCI, where each instance of
the SCI indicates the first COT. In some examples, the SCI manager
1225 may transmit, during the second COT, an indication that the
first resource is used or unused for retransmission of the first
communication. In some examples, the SCI manager 1225 of the second
UE may receive, from the first UE, SCI that indicates one or more
of the first COT, the second COT, the indication of the first
reserved resource, or any combinations thereof
[0135] In some cases, each instance of the SCI indicates an offset
between the instance of the SCI and a start of the first COT. In
some cases, the indication is provided in SCI that is transmitted
during the second COT. In some cases, the SCI includes a bitmap
that provides the indication, where each bit of the bitmap
corresponds to a reserved resource in the second COT. In some
cases, the first UE transmits two or more instances of the SCI,
where each instance of the SCI indicates the first COT and an
offset between the instance of the SCI and a start of a COT
associated with the SCI.
[0136] The LBT manager 1230 may determine that a LBT procedure
associated with the second COT has obtained the shared radio
frequency spectrum band for the sidelink communications. In some
examples, the LBT manager 1230 may determine the start time of the
second COT based on a completion time of the LBT procedure.
[0137] The shared COT manager 1235 may receive, from the third UE,
SCI that identifies the second COT and a shared COT for the
sidelink communications in the shared radio frequency spectrum
band. In some cases, the second COT is obtained by a third UE for
sidelink communications in the shared radio frequency spectrum
band. In some cases, the timing of the first resource is based on
the SCI from the third UE. In some cases, the first resource is
indicated by a slot offset to a COT that is obtained by a different
UE. In some cases, the first resource is indicated by a slot offset
to a boundary of the second COT that is obtained by the third UE.
In some cases, the first resource is indicated by a slot offset
from a start of the shared COT that is indicated by the third UE.
In some cases, the SCI from the third UE indicates a duration of
the shared COT, and where the timing of the first resource is
determined based on the duration of the shared COT.
[0138] The location manager 1240 may receive, from a third UE, SCI
that indicates a shared COT and a zone identification. In some
examples, the location manager 1240 may determine whether the
shared COT is available as the second COT based on the zone
identification. In some examples, the location manager 1240 may
determine that a distance between the first UE and a location
associated with the zone identification is less than a threshold
value, and where the shared COT is available as the second COT
based on the distance being less than the threshold value. In some
examples, the location manager 1240 may determine, based on a GNSS,
a first location of the first UE, and where the determining that
the distance is less than the threshold value is based on the first
location and the location associated with the zone
identification.
[0139] In some examples, the location manager 1240 may receive,
from a third UE, SCI that indicates a shared COT and a zone
identification. In some examples, the location manager 1240 may
determine whether the shared COT is available as the second COT
based on the zone identification. In some cases, the location
associated with the zone identification is a location of the third
UE. In some cases, the zone identification corresponds to a group
identification provided by a network node, and where the shared COT
is available as the second COT when the group identification of the
first UE is the same as the group identification of the third
UE.
[0140] In some cases, the SCI from the third UE is forwarded by one
or more other UEs. In some cases, the one or more other UEs act as
relay nodes for the SCI and include a UE identification of the
third UE that obtained the second COT.
[0141] In some cases, the zone identification corresponds to a
group identification provided by a network node, and where the
shared COT is available as the second COT when the group
identification of the first UE is the same as the group
identification of the third UE. In some cases, the SCI from the
third UE is forwarded by one or more other UEs.
[0142] FIG. 13 shows a diagram of a system 1300 including a device
1305 that supports resource reservation for sidelink communications
in shared radio frequency spectrum in accordance with aspects of
the present disclosure. The device 1305 may be an example of or
include the components of device 1005, device 1105, or a UE 115 as
described herein. The device 1305 may include components for
bi-directional voice and data communications including components
for transmitting and receiving communications, including a
communications manager 1310, an I/O controller 1315, a transceiver
1320, an antenna 1325, memory 1330, and a processor 1340. These
components may be in electronic communication via one or more buses
(e.g., bus 1345).
[0143] The communications manager 1310 may transmit a first
communication to at least a second UE during a first COT of the
first UE for sidelink communications in a shared radio frequency
spectrum band, reserve at least a first resource for a
retransmission of the first communication in a second COT for
sidelink communications in the shared radio frequency spectrum
band, where the first resource is indicated relative to a start
time of the second COT, determine, after the reserving, the start
time of the second COT in the shared radio frequency spectrum band,
identify a timing for the first resource based on the determined
start time of the second COT, and retransmit the first
communication to at least the second UE using the first
resource.
[0144] The communications manager 1310 may also receive, from a
first UE, a first communication during a first COT for sidelink
communications in a shared radio frequency spectrum band, receive,
from the first UE, an indication of at least a first reserved
resource for a retransmission of the first communication in a
second COT for sidelink communications in the shared radio
frequency spectrum band, where the first reserved resource is
indicated relative to a start time of the second COT, determine,
after the first COT, the start time of the second COT in the shared
radio frequency spectrum band, and identify a timing for the first
reserved resource based on the determined start time of the second
COT.
[0145] The communications manager 1315 as described herein may be
implemented to realize one or more potential advantages. One
implementation may allow the device 1305 to reliably determine
reserved resources for one or more retransmissions for one or more
sidelink communications. Such operations may provide improvements
to reliability and efficiency in communications with sidelink UEs
and with other UEs that may transmit or receive high priority or
low latency communications using shared radio frequency spectrum or
that otherwise gain channel access through a contention-based
channel access procedure.
[0146] Such improvements may enhance efficiency of wireless
communications at a UE by allowing for reliable identification of
reserved resources in the sidelink resources. As such, supported
techniques may include improved network and UE operations and, in
some examples, may promote network efficiencies, reduce latency,
and provide network scheduling flexibility, among other
benefits.
[0147] The I/O controller 1315 may manage input and output signals
for the device 1305. The I/O controller 1315 may also manage
peripherals not integrated into the device 1305. In some cases, the
I/O controller 1315 may represent a physical connection or port to
an external peripheral. In some cases, the I/O controller 1315 may
utilize an operating system such as iOS.RTM., ANDROID.RTM.,
MS-DOS.RTM., MS-WINDOWS.RTM., OS/2.RTM., UNIX.RTM., LINUX.RTM., or
another known operating system. In other cases, the I/O controller
1315 may represent or interact with a modem, a keyboard, a mouse, a
touchscreen, or a similar device. In some cases, the I/O controller
1315 may be implemented as part of a processor. In some cases, a
user may interact with the device 1305 via the I/O controller 1315
or via hardware components controlled by the I/O controller
1315.
[0148] The transceiver 1320 may communicate bi-directionally, via
one or more antennas, wired, or wireless links as described herein.
For example, the transceiver 1320 may represent a wireless
transceiver and may communicate bi-directionally with another
wireless transceiver. The transceiver 1320 may also include a modem
to modulate the packets and provide the modulated packets to the
antennas for transmission, and to demodulate packets received from
the antennas.
[0149] In some cases, the wireless device may include a single
antenna 1325. However, in some cases the device may have more than
one antenna 1325, which may be capable of concurrently transmitting
or receiving multiple wireless transmissions.
[0150] The memory 1330 may include RAM and ROM. The memory 1330 may
store computer-readable, computer-executable code 1335 including
instructions that, when executed, cause the processor to perform
various functions described herein. In some cases, the memory 1330
may contain, among other things, a BIOS which may control basic
hardware or software operation such as the interaction with
peripheral components or devices.
[0151] The processor 1340 may include an intelligent hardware
device, (e.g., a general-purpose processor, a DSP, a CPU, a
microcontroller, an ASIC, an FPGA, a programmable logic device, a
discrete gate or transistor logic component, a discrete hardware
component, or any combination thereof). In some cases, the
processor 1340 may be configured to operate a memory array using a
memory controller. In other cases, a memory controller may be
integrated into the processor 1340. The processor 1340 may be
configured to execute computer-readable instructions stored in a
memory (e.g., the memory 1330) to cause the device 1305 to perform
various functions (e.g., functions or tasks supporting resource
reservation for sidelink communications in shared radio frequency
spectrum).
[0152] The code 1335 may include instructions to implement aspects
of the present disclosure, including instructions to support
wireless communications. The code 1335 may be stored in a
non-transitory computer-readable medium such as system memory or
other type of memory. In some cases, the code 1335 may not be
directly executable by the processor 1340 but may cause a computer
(e.g., when compiled and executed) to perform functions described
herein.
[0153] FIG. 14 shows a flowchart illustrating a method 1400 that
supports resource reservation for sidelink communications in shared
radio frequency spectrum in accordance with aspects of the present
disclosure. The operations of method 1400 may be implemented by a
UE 115 or its components as described herein. For example, the
operations of method 1400 may be performed by a communications
manager as described with reference to
[0154] FIGS. 10 through 13. In some examples, a UE may execute a
set of instructions to control the functional elements of the UE to
perform the described functions. Additionally or alternatively, a
UE may perform aspects of the described functions using
special-purpose hardware.
[0155] At 1405, the UE may transmit a first communication to at
least a second UE during a first COT of the first UE for sidelink
communications in a shared radio frequency spectrum band. The
operations of 1405 may be performed according to the methods
described herein. In some examples, aspects of the operations of
1405 may be performed by a sidelink communications manager as
described with reference to FIGS. 10 through 13.
[0156] At 1410, the UE may reserve at least a first resource for a
retransmission of the first communication in a second COT for
sidelink communications in the shared radio frequency spectrum
band, where the first resource is indicated relative to a start
time of the second COT. The operations of 1410 may be performed
according to the methods described herein. In some examples,
aspects of the operations of 1410 may be performed by a resource
reservation manager as described with reference to FIGS. 10 through
13.
[0157] At 1415, the UE may determine, after the reserving, the
start time of the second COT in the shared radio frequency spectrum
band. The operations of 1415 may be performed according to the
methods described herein. In some examples, aspects of the
operations of 1415 may be performed by a COT manager as described
with reference to FIGS. 10 through 13.
[0158] At 1420, the UE may identify a timing for the first resource
based on the determined start time of the second COT. The
operations of 1420 may be performed according to the methods
described herein. In some examples, aspects of the operations of
1420 may be performed by a resource reservation manager as
described with reference to FIGS. 10 through 13.
[0159] At 1425, the UE may retransmit the first communication to at
least the second UE using the first resource. The operations of
1425 may be performed according to the methods described herein. In
some examples, aspects of the operations of 1425 may be performed
by a sidelink communications manager as described with reference to
FIGS. 10 through 13.
[0160] FIG. 15 shows a flowchart illustrating a method 1500 that
supports resource reservation for sidelink communications in shared
radio frequency spectrum in accordance with aspects of the present
disclosure. The operations of method 1500 may be implemented by a
UE 115 or its components as described herein. For example, the
operations of method 1500 may be performed by a communications
manager as described with reference to FIGS. 10 through 13. In some
examples, a UE may execute a set of instructions to control the
functional elements of the UE to perform the described functions.
Additionally or alternatively, a UE may perform aspects of the
described functions using special-purpose hardware.
[0161] At 1505, the UE may transmit a first communication to at
least a second UE during a first COT of the first UE for sidelink
communications in a shared radio frequency spectrum band. The
operations of 1505 may be performed according to the methods
described herein. In some examples, aspects of the operations of
1505 may be performed by a sidelink communications manager as
described with reference to FIGS. 10 through 13. In some cases, the
UE may transmit, within the first COT, two or more instances of the
SCI, where each instance of the SCI indicates the first COT. In
some cases, each instance of the SCI indicates an offset between
the instance of the SCI and a start of the first COT.
[0162] At 1510, the UE may reserve at least a first resource for a
retransmission of the first communication in a second COT for
sidelink communications in the shared radio frequency spectrum
band, where the first resource is indicated relative to a start
time of the second COT. The operations of 1510 may be performed
according to the methods described herein. In some examples,
aspects of the operations of 1510 may be performed by a resource
reservation manager as described with reference to FIGS. 10 through
13.
[0163] At 1515, the UE may determine, after the reserving, the
start time of the second COT in the shared radio frequency spectrum
band. The operations of 1515 may be performed according to the
methods described herein. In some examples, aspects of the
operations of 1515 may be performed by a COT manager as described
with reference to FIGS. 10 through 13.
[0164] At 1520, the UE may transmit, to one or more other UEs, SCI
that indicates one or more of the first COT or the second COT. The
operations of 1520 may be performed according to the methods
described herein. In some examples, aspects of the operations of
1520 may be performed by a SCI manager as described with reference
to FIGS. 10 through 13.
[0165] At 1525, the UE may identify a timing for the first resource
based on the determined start time of the second COT. The
operations of 1525 may be performed according to the methods
described herein. In some examples, aspects of the operations of
1525 may be performed by a resource reservation manager as
described with reference to FIGS. 10 through 13.
[0166] At 1530, the UE may retransmit the first communication to at
least the second UE using the first resource. The operations of
1530 may be performed according to the methods described herein. In
some examples, aspects of the operations of 1530 may be performed
by a sidelink communications manager as described with reference to
FIGS. 10 through 13.
[0167] FIG. 16 shows a flowchart illustrating a method 1600 that
supports resource reservation for sidelink communications in shared
radio frequency spectrum in accordance with aspects of the present
disclosure. The operations of method 1600 may be implemented by a
UE 115 or its components as described herein. For example, the
operations of method 1600 may be performed by a communications
manager as described with reference to FIGS. 10 through 13. In some
examples, a UE may execute a set of instructions to control the
functional elements of the UE to perform the described functions.
Additionally or alternatively, a UE may perform aspects of the
described functions using special-purpose hardware.
[0168] At 1605, the UE may transmit a first communication to at
least a second UE during a first COT of the first UE for sidelink
communications in a shared radio frequency spectrum band. The
operations of 1605 may be performed according to the methods
described herein. In some examples, aspects of the operations of
1605 may be performed by a sidelink communications manager as
described with reference to FIGS. 10 through 13.
[0169] At 1610, the UE may reserve at least a first resource for a
retransmission of the first communication in a second COT for
sidelink communications in the shared radio frequency spectrum
band, where the first resource is indicated relative to a start
time of the second COT. The operations of 1610 may be performed
according to the methods described herein. In some examples,
aspects of the operations of 1610 may be performed by a resource
reservation manager as described with reference to FIGS. 10 through
13.
[0170] At 1615, the UE may determine that a listen-before-talk
procedure associated with the second COT has obtained the shared
radio frequency spectrum band for the sidelink communications. The
operations of 1615 may be performed according to the methods
described herein. In some examples, aspects of the operations of
1615 may be performed by a LBT manager as described with reference
to FIGS. 10 through 13.
[0171] At 1620, the UE may determine the start time of the second
COT based on a completion time of the listen-before-talk procedure.
The operations of 1620 may be performed according to the methods
described herein. In some examples, aspects of the operations of
1620 may be performed by a LBT manager as described with reference
to FIGS. 10 through 13.
[0172] At 1625, the UE may identify a timing for the first resource
based on the determined start time of the second COT. The
operations of 1625 may be performed according to the methods
described herein. In some examples, aspects of the operations of
1625 may be performed by a resource reservation manager as
described with reference to FIGS. 10 through 13.
[0173] At 1630, the UE may retransmit the first communication to at
least the second UE using the first resource. The operations of
1630 may be performed according to the methods described herein. In
some examples, aspects of the operations of 1630 may be performed
by a sidelink communications manager as described with reference to
FIGS. 10 through 13.
[0174] FIG. 17 shows a flowchart illustrating a method 1700 that
supports resource reservation for sidelink communications in shared
radio frequency spectrum in accordance with aspects of the present
disclosure. The operations of method 1700 may be implemented by a
UE 115 or its components as described herein. For example, the
operations of method 1700 may be performed by a communications
manager as described with reference to FIGS. 10 through 13. In some
examples, a UE may execute a set of instructions to control the
functional elements of the UE to perform the described functions.
Additionally or alternatively, a UE may perform aspects of the
described functions using special-purpose hardware.
[0175] At 1705, the UE may transmit a first communication to at
least a second UE during a first COT of the first UE for sidelink
communications in a shared radio frequency spectrum band. The
operations of 1705 may be performed according to the methods
described herein. In some examples, aspects of the operations of
1705 may be performed by a sidelink communications manager as
described with reference to FIGS. 10 through 13.
[0176] At 1710, the UE may reserve at least a first resource for a
retransmission of the first communication in a second COT for
sidelink communications in the shared radio frequency spectrum
band, where the first resource is indicated relative to a start
time of the second COT. The operations of 1710 may be performed
according to the methods described herein. In some examples,
aspects of the operations of 1710 may be performed by a resource
reservation manager as described with reference to FIGS. 10 through
13.
[0177] At 1715, the UE may determine, after the reserving, the
start time of the second COT in the shared radio frequency spectrum
band. The operations of 1715 may be performed according to the
methods described herein. In some examples, aspects of the
operations of 1715 may be performed by a COT manager as described
with reference to FIGS. 10 through 13.
[0178] At 1720, the UE may identify a timing for the first resource
based on the determined start time of the second COT. The
operations of 1720 may be performed according to the methods
described herein. In some examples, aspects of the operations of
1720 may be performed by a resource reservation manager as
described with reference to FIGS. 10 through 13.
[0179] At 1725, the UE may transmit, during the second COT, an
indication that the first resource is used or unused for
retransmission of the first communication. The operations of 1725
may be performed according to the methods described herein. In some
examples, aspects of the operations of 1725 may be performed by a
SCI manager as described with reference to FIGS. 10 through 13. In
some cases, the indication is provided in SCI that is transmitted
during the second COT. In some cases, the SCI includes a bitmap
that provides the indication, where each bit of the bitmap
corresponds to a reserved resource in the second COT.
[0180] At 1730, the UE may retransmit the first communication to at
least the second UE using the first resource. The operations of
1730 may be performed according to the methods described herein. In
some examples, aspects of the operations of 1730 may be performed
by a sidelink communications manager as described with reference to
FIGS. 10 through 13.
[0181] FIG. 18 shows a flowchart illustrating a method 1800 that
supports resource reservation for sidelink communications in shared
radio frequency spectrum in accordance with aspects of the present
disclosure. The operations of method 1800 may be implemented by a
UE 115 or its components as described herein. For example, the
operations of method 1800 may be performed by a communications
manager as described with reference to FIGS. 10 through 13. In some
examples, a UE may execute a set of instructions to control the
functional elements of the UE to perform the described functions.
Additionally or alternatively, a UE may perform aspects of the
described functions using special-purpose hardware.
[0182] At 1805, the UE may transmit a first communication to at
least a second UE during a first COT of the first UE for sidelink
communications in a shared radio frequency spectrum band. The
operations of 1805 may be performed according to the methods
described herein. In some examples, aspects of the operations of
1805 may be performed by a sidelink communications manager as
described with reference to FIGS. 10 through 13.
[0183] At 1810, the UE may reserve at least a first resource for a
retransmission of the first communication in a second COT for
sidelink communications in the shared radio frequency spectrum
band, where the first resource is indicated relative to a start
time of the second COT. The operations of 1810 may be performed
according to the methods described herein. In some examples,
aspects of the operations of 1810 may be performed by a resource
reservation manager as described with reference to FIGS. 10 through
13.
[0184] At 1815, the UE may receive, from a third UE, SCI that
identifies the second COT and a shared COT for the sidelink
communications in the shared radio frequency spectrum band. The
operations of 1815 may be performed according to the methods
described herein. In some examples, aspects of the operations of
1815 may be performed by a shared COT manager as described with
reference to FIGS. 10 through 13.
[0185] At 1820, the UE may determine, after the reserving, the
start time of the second COT in the shared radio frequency spectrum
band. The operations of 1820 may be performed according to the
methods described herein. In some examples, aspects of the
operations of 1820 may be performed by a COT manager as described
with reference to FIGS. 10 through 13. In some cases, the second
COT is obtained based on the SCI from the third UE.
[0186] At 1825, the UE may identify a timing for the first resource
based on the determined start time of the second COT. The
operations of 1825 may be performed according to the methods
described herein. In some examples, aspects of the operations of
1825 may be performed by a resource reservation manager as
described with reference to FIGS. 10 through 13.
[0187] At 1830, the UE may retransmit the first communication to at
least the second UE using the first resource. The operations of
1830 may be performed according to the methods described herein. In
some examples, aspects of the operations of 1830 may be performed
by a sidelink communications manager as described with reference to
FIGS. 10 through 13.
[0188] FIG. 19 shows a flowchart illustrating a method 1900 that
supports resource reservation for sidelink communications in shared
radio frequency spectrum in accordance with aspects of the present
disclosure. The operations of method 1900 may be implemented by a
UE 115 or its components as described herein. For example, the
operations of method 1900 may be performed by a communications
manager as described with reference to FIGS. 10 through 13. In some
examples, a UE may execute a set of instructions to control the
functional elements of the UE to perform the described functions.
Additionally or alternatively, a UE may perform aspects of the
described functions using special-purpose hardware.
[0189] At 1905, the UE may transmit a first communication to at
least a second UE during a first COT of the first UE for sidelink
communications in a shared radio frequency spectrum band. The
operations of 1905 may be performed according to the methods
described herein. In some examples, aspects of the operations of
1905 may be performed by a sidelink communications manager as
described with reference to FIGS. 10 through 13.
[0190] At 1910, the UE may reserve at least a first resource for a
retransmission of the first communication in a second COT for
sidelink communications in the shared radio frequency spectrum
band, where the first resource is indicated relative to a start
time of the second COT. The operations of 1910 may be performed
according to the methods described herein. In some examples,
aspects of the operations of 1910 may be performed by a resource
reservation manager as described with reference to FIGS. 10 through
13.
[0191] At 1915, the UE may receive, from a third UE, SCI that
indicates a shared COT and a zone identification. The operations of
1915 may be performed according to the methods described herein. In
some examples, aspects of the operations of 1915 may be performed
by a location manager as described with reference to FIGS. 10
through 13.
[0192] At 1920, the UE may determine that a distance between the
first UE and a location associated with the zone identification is
less than a threshold value, and where the shared COT is available
as the second COT based on the distance being less than the
threshold value. The operations of 1920 may be performed according
to the methods described herein. In some examples, aspects of the
operations of 1920 may be performed by a location manager as
described with reference to FIGS. 10 through 13.
[0193] At 1925, the UE may determine whether the shared COT is
available as the second COT based on the zone identification. The
operations of 1925 may be performed according to the methods
described herein. In some examples, aspects of the operations of
1925 may be performed by a location manager as described with
reference to FIGS. 10 through 13.
[0194] At 1930, the UE may identify a timing for the first resource
based on the determined start time of the second COT. The
operations of 1930 may be performed according to the methods
described herein. In some examples, aspects of the operations of
1930 may be performed by a resource reservation manager as
described with reference to FIGS. 10 through 13.
[0195] At 1935, the UE may retransmit the first communication to at
least the second UE using the first resource. The operations of
1935 may be performed according to the methods described herein. In
some examples, aspects of the operations of 1935 may be performed
by a sidelink communications manager as described with reference to
FIGS. 10 through 13.
[0196] FIG. 20 shows a flowchart illustrating a method 2000 that
supports resource reservation for sidelink communications in shared
radio frequency spectrum in accordance with aspects of the present
disclosure. The operations of method 2000 may be implemented by a
UE 115 or its components as described herein. For example, the
operations of method 2000 may be performed by a communications
manager as described with reference to FIGS. 10 through 13. In some
examples, a UE may execute a set of instructions to control the
functional elements of the UE to perform the described functions.
Additionally or alternatively, a UE may perform aspects of the
described functions using special-purpose hardware.
[0197] At 2005, the UE may receive, from a first UE, a first
communication during a first COT for sidelink communications in a
shared radio frequency spectrum band. The operations of 2005 may be
performed according to the methods described herein. In some
examples, aspects of the operations of 2005 may be performed by a
sidelink communications manager as described with reference to
FIGS. 10 through 13.
[0198] At 2010, the UE may receive, from the first UE, an
indication of at least a first reserved resource for a
retransmission of the first communication in a second COT for
sidelink communications in the shared radio frequency spectrum
band, where the first reserved resource is indicated relative to a
start time of the second COT. The operations of 2010 may be
performed according to the methods described herein. In some
examples, aspects of the operations of 2010 may be performed by a
resource reservation manager as described with reference to FIGS.
10 through 13.
[0199] At 2015, the UE may determine, after the first COT, the
start time of the second COT in the shared radio frequency spectrum
band. The operations of 2015 may be performed according to the
methods described herein. In some examples, aspects of the
operations of 2015 may be performed by a COT manager as described
with reference to FIGS. 10 through 13.
[0200] At 2020, the UE may identify a timing for the first reserved
resource based on the determined start time of the second COT. The
operations of 2020 may be performed according to the methods
described herein. In some examples, aspects of the operations of
2020 may be performed by a resource reservation manager as
described with reference to FIGS. 10 through 13.
[0201] FIG. 21 shows a flowchart illustrating a method 2100 that
supports resource reservation for sidelink communications in shared
radio frequency spectrum in accordance with aspects of the present
disclosure. The operations of method 2100 may be implemented by a
UE 115 or its components as described herein. For example, the
operations of method 2100 may be performed by a communications
manager as described with reference to FIGS. 10 through 13. In some
examples, a UE may execute a set of instructions to control the
functional elements of the UE to perform the described functions.
Additionally or alternatively, a UE may perform aspects of the
described functions using special-purpose hardware.
[0202] At 2105, the UE may receive, from a first UE, a first
communication during a first COT for sidelink communications in a
shared radio frequency spectrum band. The operations of 2105 may be
performed according to the methods described herein. In some
examples, aspects of the operations of 2105 may be performed by a
sidelink communications manager as described with reference to
FIGS. 10 through 13.
[0203] At 2110, the UE may receive, from the first UE, an
indication of at least a first reserved resource for a
retransmission of the first communication in a second COT for
sidelink communications in the shared radio frequency spectrum
band, where the first reserved resource is indicated relative to a
start time of the second COT. The operations of 2110 may be
performed according to the methods described herein. In some
examples, aspects of the operations of 2110 may be performed by a
resource reservation manager as described with reference to FIGS.
10 through 13.
[0204] At 2115, the UE may receive, from the first UE, SCI that
indicates one or more of the first COT, the second COT, the
indication of the first reserved resource, or any combinations
thereof. The operations of 2115 may be performed according to the
methods described herein. In some examples, aspects of the
operations of 2115 may be performed by a SCI manager as described
with reference to FIGS. 10 through 13.
[0205] At 2120, the UE may determine, after the first COT, the
start time of the second COT in the shared radio frequency spectrum
band. The operations of 2120 may be performed according to the
methods described herein. In some examples, aspects of the
operations of 2120 may be performed by a COT manager as described
with reference to FIGS. 10 through 13.
[0206] At 2125, the UE may identify a timing for the first reserved
resource based on the determined start time of the second COT. The
operations of 2125 may be performed according to the methods
described herein. In some examples, aspects of the operations of
2125 may be performed by a resource reservation manager as
described with reference to FIGS. 10 through 13.
[0207] FIG. 22 shows a flowchart illustrating a method 2200 that
supports resource reservation for sidelink communications in shared
radio frequency spectrum in accordance with aspects of the present
disclosure. The operations of method 2200 may be implemented by a
UE 115 or its components as described herein. For example, the
operations of method 2200 may be performed by a communications
manager as described with reference to FIGS. 10 through 13. In some
examples, a UE may execute a set of instructions to control the
functional elements of the UE to perform the described functions.
Additionally or alternatively, a UE may perform aspects of the
described functions using special-purpose hardware.
[0208] At 2205, the UE may receive, from a first UE, a first
communication during a first COT for sidelink communications in a
shared radio frequency spectrum band. The operations of 2205 may be
performed according to the methods described herein. In some
examples, aspects of the operations of 2205 may be performed by a
sidelink communications manager as described with reference to
FIGS. 10 through 13.
[0209] At 2210, the UE may receive, from the first UE, an
indication of at least a first reserved resource for a
retransmission of the first communication in a second COT for
sidelink communications in the shared radio frequency spectrum
band, where the first reserved resource is indicated relative to a
start time of the second COT. The operations of 2210 may be
performed according to the methods described herein. In some
examples, aspects of the operations of 2210 may be performed by a
resource reservation manager as described with reference to FIGS.
10 through 13.
[0210] At 2215, the UE may receive, from a third UE, SCI that
indicates a shared COT and a zone identification. The operations of
2215 may be performed according to the methods described herein. In
some examples, aspects of the operations of 2215 may be performed
by a location manager as described with reference to FIGS. 10
through 13.
[0211] At 2220, the UE may determine whether the shared COT is
available as the second COT based on the zone identification. The
operations of 2220 may be performed according to the methods
described herein. In some examples, aspects of the operations of
2220 may be performed by a location manager as described with
reference to FIGS. 10 through 13.
[0212] At 2225, the UE may identify a timing for the first reserved
resource based on the determined start time of the second COT. The
operations of 2225 may be performed according to the methods
described herein. In some examples, aspects of the operations of
2225 may be performed by a resource reservation manager as
described with reference to FIGS. 10 through 13.
[0213] It should be noted that the methods described herein
describe possible implementations, and that the operations and the
steps may be rearranged or otherwise modified and that other
implementations are possible. Further, aspects from two or more of
the methods may be combined.
[0214] The following provides an overview of aspects of the present
disclosure:
[0215] Aspect 1: A method for wireless communication at a first UE,
comprising: transmitting a first communication to at least a second
UE during a first channel occupancy time of the first UE for
sidelink communications in a shared radio frequency spectrum band;
reserving at least a first resource for a retransmission of the
first communication in a second channel occupancy time for sidelink
communications in the shared radio frequency spectrum band, wherein
the first resource is indicated relative to a start time of the
second channel occupancy time; determining, after the reserving,
the start time of the second channel occupancy time in the shared
radio frequency spectrum band; and retransmitting the first
communication to at least the second UE using the first resource,
wherein a timing for the first resource is based at least in part
on the determined start time of the second channel occupancy
time.
[0216] Aspect 2: The method of aspect 1, further comprising:
transmitting, to one or more other UEs, sidelink control
information that indicates one or more of the first channel
occupancy time or the second channel occupancy time.
[0217] Aspect 3: The method of aspect 2, wherein the transmitting
the sidelink control information comprises: transmitting, within
the first channel occupancy time, two or more instances of the
sidelink control information, wherein each instance of the sidelink
control information indicates the first channel occupancy time.
[0218] Aspect 4: The method of aspect 3, wherein each instance of
the sidelink control information indicates an offset between the
instance of the sidelink control information and a start of the
first channel occupancy time.
[0219] Aspect 5: The method of any of aspects 1 through 4, wherein
the reserving the first resource comprises: transmitting, to one or
more other UEs, an indication of a relative slot offset between the
start time of the second channel occupancy time and the first
resource.
[0220] Aspect 6: The method of aspect 5, wherein the indication of
the relative slot offset between the start time of the second
channel occupancy time and the first resource is indicated in a
sidelink control information transmission.
[0221] Aspect 7: The method of any of aspects 1 through 6, wherein
the determining the start time of the second channel occupancy time
comprises: determining that a listen-before-talk procedure
associated with the second channel occupancy time has obtained the
shared radio frequency spectrum band for the sidelink
communications; and determining the start time of the second
channel occupancy time based at least in part on a completion time
of the listen-before-talk procedure.
[0222] Aspect 8: The method of any of aspects 1 through 7, wherein
the first resource expires based at least in part on a
predetermined window after the first communication, and the
predetermined window corresponds to a predetermined number of
channel occupancy times after the first communication, a
predetermined time period after the first communication, or any
combinations thereof
[0223] Aspect 9: The method of any of aspects 1 through 8, further
comprising: transmitting, during the second channel occupancy time,
an indication that the first resource is used or unused for
retransmission of the first communication, wherein the indication
is provided in sidelink control information that is transmitted
during the second channel occupancy time.
[0224] Aspect 10: The method of aspect 9, wherein the sidelink
control information includes a bitmap that provides the indication,
each bit of the bitmap corresponds to a reserved resource in the
second channel occupancy time.
[0225] Aspect 11: The method of any of aspects 1 through 10,
wherein the second channel occupancy time is obtained by a third UE
for sidelink communications in the shared radio frequency spectrum
band, and wherein the method further comprises: receiving, from the
third UE, sidelink control information that identifies the second
channel occupancy time and a shared channel occupancy time for the
sidelink communications in the shared radio frequency spectrum
band.
[0226] Aspect 12: The method of aspect 11, wherein the timing of
the first resource is based at least in part on the sidelink
control information from the third UE, and the first resource is
indicated by one or more of a slot offset to a channel occupancy
time that is obtained by a different UE, a slot offset to a
boundary of the second channel occupancy time that is obtained by
the third UE, or a slot offset from a start of the shared channel
occupancy time that is indicated by the third UE.
[0227] Aspect 13: The method of aspect 12, wherein the sidelink
control information from the third UE indicates a duration of the
shared channel occupancy time, and the timing of the first resource
is determined based at least in part on the duration of the shared
channel occupancy time.
[0228] Aspect 14: The method of any of aspects 12 through 13,
wherein a reservation of the first resource expires based at least
in part on a predetermined window after the first communication,
one or more shared channel occupancy times subsequent to the first
communication, or any combinations thereof
[0229] Aspect 15: The method of any of aspects 1 through 14,
further comprising: receiving, from a third UE, sidelink control
information that indicates a shared channel occupancy time and a
zone identification; and determining whether the shared channel
occupancy time is available as the second channel occupancy time
based at least in part on the zone identification.
[0230] Aspect 16: The method of aspect 15, further comprising:
determining that a distance between the first UE and a location
associated with the zone identification is less than a threshold
value, and wherein the shared channel occupancy time is available
as the second channel occupancy time based at least in part on the
distance being less than the threshold value.
[0231] Aspect 17: A method for wireless communication at a second
UE, comprising: receiving, from a first UE, a first communication
during a first channel occupancy time for sidelink communications
in a shared radio frequency spectrum band; receiving, from the
first UE, an indication of at least a first reserved resource for a
retransmission of the first communication in a second channel
occupancy time for sidelink communications in the shared radio
frequency spectrum band, wherein the first reserved resource is
indicated relative to a start time of the second channel occupancy
time; determining, after the first channel occupancy time, the
start time of the second channel occupancy time in the shared radio
frequency spectrum band; and identifying a timing for the first
reserved resource based at least in part on the determined start
time of the second channel occupancy time.
[0232] Aspect 18: The method of aspect 17, further comprising:
receiving, from the first UE, sidelink control information that
indicates one or more of the first channel occupancy time, the
second channel occupancy time, the indication of the first reserved
resource, or any combinations thereof
[0233] Aspect 19: The method of aspect 18, wherein the first UE
transmits two or more instances of the sidelink control
information, each instance of the sidelink control information
indicates the first channel occupancy time and an offset between
the instance of the sidelink control information and a start of a
channel occupancy time associated with the sidelink control
information.
[0234] Aspect 20: The method of any of aspects 17 through 19,
wherein the indication of at least the first reserved resource
includes a relative slot offset between the start time of the
second channel occupancy time and the first reserved resource.
[0235] Aspect 21: The method of any of aspects 17 through 20,
wherein the first reserved resource expires based at least in part
on a predetermined window after the first communication, and the
predetermined window corresponds to a predetermined number of
channel occupancy times after the first communication, a
predetermined time period after the first communication, or any
combinations thereof
[0236] Aspect 22: The method of any of aspects 17 through 21,
further comprising: receiving, during the second channel occupancy
time, an indication that the first reserved resource is used or
unused for retransmission of the first communication; and
monitoring for the retransmission of the first communication based
on the indication that the first reserved resource is used for the
retransmission of the first communication.
[0237] Aspect 23: The method of any of aspects 17 through 22,
wherein the second channel occupancy time is obtained by a third UE
for sidelink communications in the shared radio frequency spectrum
band, and wherein the method further comprises: receiving, from the
third UE, sidelink control information that identifies the second
channel occupancy time and a shared channel occupancy time for the
sidelink communications in the shared radio frequency spectrum
band.
[0238] Aspect 24: The method of any of aspects 17 through 23,
further comprising: receiving, from a third UE, sidelink control
information that indicates a shared channel occupancy time and a
zone identification; and determining whether the shared channel
occupancy time is available as the second channel occupancy time
based at least in part on the zone identification.
[0239] Aspect 25: An apparatus for wireless communication at a
first UE, comprising a processor; memory coupled with the
processor; and instructions stored in the memory and executable by
the processor to cause the apparatus to perform a method of any of
aspects 1 through 16.
[0240] Aspect 26: An apparatus for wireless communication at a
first UE, comprising at least one means for performing a method of
any of aspects 1 through 16.
[0241] Aspect 27: A non-transitory computer-readable medium storing
code for wireless communication at a first UE, the code comprising
instructions executable by a processor to perform a method of any
of aspects 1 through 16.
[0242] Aspect 28: An apparatus for wireless communication at a
second UE, comprising a processor; memory coupled with the
processor; and instructions stored in the memory and executable by
the processor to cause the apparatus to perform a method of any of
aspects 17 through 24.
[0243] Aspect 29: An apparatus for wireless communication at a
second UE, comprising at least one means for performing a method of
any of aspects 17 through 24.
[0244] Aspect 30: A non-transitory computer-readable medium storing
code for wireless communication at a second UE, the code comprising
instructions executable by a processor to perform a method of any
of aspects 17 through 24.
[0245] Although aspects of an LTE, LTE-A, LTE-A Pro, or NR system
may be described for purposes of example, and LTE, LTE-A, LTE-A
Pro, or NR terminology may be used in much of the description, the
techniques described herein are applicable beyond LTE, LTE-A, LTE-A
Pro, or NR networks. For example, the described techniques may be
applicable to various other wireless communications systems such as
Ultra Mobile Broadband (UMB), Institute of Electrical and
Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX),
IEEE 802.20, Flash-OFDM, as well as other systems and radio
technologies not explicitly mentioned herein.
[0246] Information and signals described herein may be represented
using any of a variety of different technologies and techniques.
For example, data, instructions, commands, information, signals,
bits, symbols, and chips that may be referenced throughout the
description may be represented by voltages, currents,
electromagnetic waves, magnetic fields or particles, optical fields
or particles, or any combination thereof
[0247] The various illustrative blocks and components described in
connection with the disclosure herein may be implemented or
performed with a general-purpose processor, a DSP, an ASIC, a CPU,
an FPGA or other programmable logic device, discrete gate or
transistor logic, discrete hardware components, or any combination
thereof designed to perform the functions described herein. A
general-purpose processor may be a microprocessor, but in the
alternative, the processor may be any processor, controller,
microcontroller, or state machine. A processor may also be
implemented as a combination of computing devices (e.g., a
combination of a DSP and a microprocessor, multiple
microprocessors, one or more microprocessors in conjunction with a
DSP core, or any other such configuration).
[0248] The functions described herein may be implemented in
hardware, software executed by a processor, firmware, or any
combination thereof. If implemented in software executed by a
processor, the functions may be stored on or transmitted over as
one or more instructions or code on a computer-readable medium.
Other examples and implementations are within the scope of the
disclosure and appended claims. For example, due to the nature of
software, functions described herein may be implemented using
software executed by a processor, hardware, firmware, hardwiring,
or combinations of any of these. Features implementing functions
may also be physically located at various positions, including
being distributed such that portions of functions are implemented
at different physical locations.
[0249] Computer-readable media includes both non-transitory
computer storage media and communication media including any medium
that facilitates transfer of a computer program from one place to
another. A non-transitory storage medium may be any available
medium that may be accessed by a general-purpose or special-purpose
computer. By way of example, and not limitation, non-transitory
computer-readable media may include random-access memory (RAM),
read-only memory (ROM), electrically erasable programmable ROM
(EEPROM), flash memory, compact disk (CD) ROM or other optical disk
storage, magnetic disk storage or other magnetic storage devices,
or any other non-transitory medium that may be used to carry or
store desired program code means in the form of instructions or
data structures and that may be accessed by a general-purpose or
special-purpose computer, or a general-purpose or special-purpose
processor. Also, any connection is properly termed a
computer-readable medium. For example, if the software is
transmitted from a website, server, or other remote source using a
coaxial cable, fiber optic cable, twisted pair, digital subscriber
line (DSL), or wireless technologies such as infrared, radio, and
microwave, then the coaxial cable, fiber optic cable, twisted pair,
DSL, or wireless technologies such as infrared, radio, and
microwave are included in the definition of computer-readable
medium. Disk and disc, as used herein, include CD, laser disc,
optical disc, digital versatile disc (DVD), floppy disk and Blu-ray
disc where disks usually reproduce data magnetically, while discs
reproduce data optically with lasers. Combinations of the above are
also included within the scope of computer-readable media.
[0250] As used herein, including in the claims, "or" as used in a
list of items (e.g., a list of items prefaced by a phrase such as
"at least one of" or "one or more of") indicates an inclusive list
such that, for example, a list of at least one of A, B, or C means
A or B or C or AB or AC or BC or ABC (i.e., A and B and C). Also,
as used herein, the phrase "based on" shall not be construed as a
reference to a closed set of conditions. For example, an example
step that is described as "based on condition A" may be based on
both a condition A and a condition B without departing from the
scope of the present disclosure. In other words, as used herein,
the phrase "based on" shall be construed in the same manner as the
phrase "based at least in part on."
[0251] In the appended figures, similar components or features may
have the same reference label. Further, various components of the
same type may be distinguished by following the reference label by
a dash and a second label that distinguishes among the similar
components. If just the first reference label is used in the
specification, the description is applicable to any one of the
similar components having the same first reference label
irrespective of the second reference label, or other subsequent
reference label.
[0252] The description set forth herein, in connection with the
appended drawings, describes example configurations and does not
represent all the examples that may be implemented or that are
within the scope of the claims. The term "example" used herein
means "serving as an example, instance, or illustration," and not
"preferred" or "advantageous over other examples." The detailed
description includes specific details for the purpose of providing
an understanding of the described techniques. These techniques,
however, may be practiced without these specific details. In some
instances, known structures and devices are shown in block diagram
form in order to avoid obscuring the concepts of the described
examples.
[0253] The description herein is provided to enable a person having
ordinary skill in the art to make or use the disclosure. Various
modifications to the disclosure will be apparent to a person having
ordinary skill in the art, and the generic principles defined
herein may be applied to other variations without departing from
the scope of the disclosure. Thus, the disclosure is not limited to
the examples and designs described herein, but is to be accorded
the broadest scope consistent with the principles and novel
features disclosed herein.
* * * * *